By the closing days of March, winter had begun to loosen its hold over the Institute, though it surrendered grudgingly, giving up an hour of daylight here and a patch of frozen ground there while leaving frost in the hollows each morning and enough cold in the wind to punish anyone foolish enough to mistake the calendar for the weather. The road leading toward the aerodrome had become a succession of dark ruts where lorries churned thawing soil into mud, water collecting beneath a colourless sky while the first uncertain buds appeared on branches that still looked dead from a distance, and whenever the wind crossed the field it carried the smells Nathan had begun to associate with the place over the previous fortnight: damp earth, petrol, hot oil and the burnt metallic stink of exhaust. Spring was coming slowly and without confidence, while the war, as far as Nathan could tell, had taken no notice.
The aerodrome itself remained deliberately modest, consisting of two timber hangars, several workshops and stores, a fuel dump positioned at what Hale considered a sensible distance and everyone responsible for carrying fuel considered an unreasonable one, and a broad stretch of improved ground gradually becoming capable of calling itself a proper flying field without embarrassing anyone involved. Telephone cables connected the workshops with the main Institute compound, another line had been reserved for security, and nothing visible from outside the perimeter identified the place for what it was; the aircraft carried no Institute markings, deliveries arrived beneath respectable paperwork and the men had been warned against discussing their employment beyond necessity. Hale had disliked the aerodrome from the moment Nathan proposed it, largely because aviation demanded the one thing the head of security could not place behind forty tonnes of steel: open sky. Nathan had once suggested that if Hale devised a method of launching an aeroplane through several floors of reinforced concrete he would happily move the programme underground, to which Hale had replied that if Nathan ever developed such a machine, storing it would probably cease to be the most important security problem attached to it.
The compromise stood around them now, isolated enough that an accident would not destroy anything irreplaceable, open enough for aircraft to operate and watched considerably more closely than its deliberately ordinary appearance suggested. Nathan had resisted expanding the programme beyond the two hangars and associated workshops because there was little value in multiplying something while everyone involved was still discovering what they did not know; buildings could be added later, staff could be hired and money could be found, whereas ignorance had the unfortunate property of scaling just as efficiently as competence.
One aircraft stood outside the nearest hangar with its engine removed, the empty forward fuselage giving it the uncomfortable appearance of something opened for dissection, while another had been chocked farther across the field where two mechanics worked around the undercarriage. The missing engine from the first machine occupied a reinforced test mounting near the workshop, its cylinders, pipes and manifolds exposed to the cold air, and considerably more steel surrounded that mounting than had been present during Nathan's first inspection. He had looked at the original arrangement, watched the engineers prepare to run an engine capable of tearing itself apart with considerable enthusiasm if something failed, and asked what would happen if the mounting gave way at full power. When told that it should not, he had asked what should not meant numerically and how the assumption had been tested, and there had been more steel the following morning.
He had also established a rule that nobody stood unnecessarily within the plane of the propeller, an instruction so obvious that several mechanics had initially regarded it as unnecessary until Nathan pointed out that familiarity possessed a remarkable ability to make intelligent men casual around dangerous things. A wooden airscrew rotating quickly enough to disappear from sight did not become less capable of cutting a man apart merely because everyone nearby understood its construction, and if anyone found the additional caution irritating Nathan was perfectly willing to accept their irritation in preference to explaining a preventable death.
T stood several yards behind him dressed exactly as everyone at the aerodrome and Institute knew him, black armour covering him from his boots to the obscured line of his neck while dark lenses concealed his eyes and the rest of his equipment occupied the same carefully selected positions it always did. Nothing loose hung from him that might catch against machinery, nothing visible offered the men around them a useful detail from which to construct an identity, and there were employees who had worked in the same compound as T for months without knowing the colour of his hair, the shape of his face or whether Taylor was even his real surname. That was intentional. The Institute was work, not a country stroll, and T did not arrive for work dressed as Joseph Taylor; as far as the overwhelming majority of the men around him were concerned, Joseph Taylor did not exist at all, and Nathan had no intention of changing that merely because the morning's work happened to take place beneath an open sky rather than behind a security barrier.
Edward Mallory, the senior engineer overseeing the morning's tests, stood beside a workbench where several drawings had been pinned beneath steel weights against the wind, while Harris, one of the younger engineers, sorted through a collection of test sheets with the expression of a man who had already learned that bringing incomplete figures into Nathan Drake's vicinity was a mistake best made once. During the previous fortnight Mallory's opinion of Nathan had moved through several recognisable stages, beginning with the professional courtesy one extended to a wealthy director who had suddenly become interested in one's work, progressing through surprise when Nathan remembered explanations given several days earlier and began using them to question explanations offered later, and arriving eventually at useful irritation once it became apparent that Nathan did not intend to become bored and wander back to biology.
Nathan preferred him irritated. An irritated expert argued, corrected and defended his reasoning, whereas a deferential one merely agreed until the expensive thing broke.
Neither Mallory nor Harris had expected Nathan to spend the better part of two weeks teaching himself enough aeronautical engineering to become troublesome, but ignorance had always struck Nathan as a temporary condition rather than something requiring embarrassment. He had begun with engines precisely because he knew very little about them, working through manuals and manufacturer reports until combustion led him toward carburation and ignition, ignition toward magnetos, compression and fuel, fuel toward detonation and heat, and heat toward cooling systems whose shape and position dragged him inevitably out of the engine and into the aerodynamics of the machine carrying it. He read about crankshafts, bearings, lubrication, cylinder construction and valves, compared inline and V arrangements, spent an evening understanding rotary engines and another working through propeller efficiency until the apparent simplicity of two shaped pieces of wood had disappeared entirely. The engineers had initially been flattered by his attention, then Nathan began asking why.
Why that material? Why that compression? Why that valve angle? Why that operating speed? Why did the bearing fail there? Why was the radiator shaped that way? Why was a particular maximum treated as a maximum, who had established it, under what conditions had they established it, had anyone tested beyond it and, if not, why was everyone calling it a limit rather than the point at which somebody had decided to stop?
By the fourth day Harris had begun carrying reference books into discussions, and Nathan had privately considered that one of the first genuinely useful results produced by the programme. I don't know was among the most valuable answers a scientist or engineer could give, provided the next action was to find out, and T had enjoyed watching the engineers discover that principle almost as much as Nathan enjoyed enforcing it.
"We can make more power; that isn't the argument," Mallory said as he tapped a figure on the latest test sheet and held the paper down when the wind tried to turn it. "The question is how long the engine remains useful after we've made it. More revolutions mean greater loads, more compression gives us another set of problems, heat rises, detonation becomes more likely, bearings suffer, valves suffer, and if all of those tolerate it then something else becomes the weak point."
"How fast?" Nathan asked, turning his attention from Mallory to the engine while the older man frowned at the apparent change of subject.
"The engine?"
"The aircraft."
"One hundred and forty-eight miles an hour on the best measured run," Harris answered after consulting a sheet he probably did not need, then added that the figure applied to the present arrangement before Nathan could ask.
"And beyond that?"
"Beyond that we struggle for every additional mile," Harris said, giving a small shrug that made the statement sound so natural Nathan almost smiled.
There it was again, the sort of sentence every sufficiently mature field eventually developed. Beyond this temperature the process became unreliable, beyond this concentration the organism died, beyond this pressure the material failed, beyond this speed they struggled for every additional mile; human beings had a peculiar habit of identifying where a problem became visible and then speaking about the location as though they had explained the cause.
"What does the Institute live by?" Nathan asked, resting one hand against the edge of the workbench while Harris looked at Mallory and Mallory looked briefly toward the engine, neither apparently certain whether Nathan was asking about some official principle they had forgotten.
Behind him, T lowered his head slightly, and Nathan glanced back at the expressionless dark lenses. "Don't help them," he said, catching the movement before T could pretend it had meant nothing.
"I wasn't going to," T replied, shifting his weight against the armour with all the innocence of a man who possessed very little.
"You were enjoying yourself."
"That isn't the same thing."
"Why?" Mallory said at last, the word arriving with a weary resignation that suggested he had finally understood the game.
"Yes. Why," Nathan answered, turning back to him. "That is what the Institute exists to answer, not these buildings, not the laboratories beneath them and certainly not me. If the engine lacks power, make it more powerful, and if someone tells you it cannot be made more powerful, ask why. If the answer is temperature, ask why the temperature cannot be controlled; if it is fuel, determine which property of the fuel is limiting you; if it is the cylinder, valve, crankshaft, bearing or lubricant, find the actual limit and determine what causes it. And if we increase the engine's power and the aircraft does not become appreciably faster, then the engine was never the only problem."
"Drag?" Harris offered, looking toward the aircraft rather than Nathan.
"Perhaps."
"Propeller efficiency?"
"Perhaps."
"Structural limitations?"
"Perhaps," Nathan repeated, nodding toward the test sheets. "Prove it. I don't want a catalogue of things which might prevent improvement; determine which ones actually do and what each costs us."
"Eventually we reach something that actually is a physical limit," Mallory said, folding his arms as though he expected Nathan to object to the existence of physics itself.
"Of course we do," Nathan replied, and the immediacy of the answer seemed to surprise him. "I am not asking you to abolish physics, Mr Mallory. I am asking you to distinguish physics from habit. We are breakers of assumptions, not facts, and if one hundred and fifty miles an hour is a genuine limit imposed by the arrangement in front of us, I want to know why. If it is simply where everybody became accustomed to saying good enough, then it isn't one."
That distinction had become one of the few pieces of culture Nathan deliberately cultivated throughout the Institute, where researchers were expected to attack their own conclusions rather than become emotionally attached to them and a failed assumption could earn genuine approval if destroying it prevented three months being wasted defending nonsense. Negative results were preserved, failed experiments recorded and inconvenient observations encouraged, because bad news belonged indoors, inside the laboratory, inside the test stand, inside the sealed chamber where the price of discovering a mistake was measured in damaged equipment and irritated scientists rather than bodies. The world outside charged considerably more for corrections.
"Engine first, then?" Harris asked, and Nathan saw something useful in the way the younger man was now looking at the aircraft; ten minutes earlier he had been looking at a machine he was expected to defend, whereas now he was looking at something that might be lying to him.
"For the immediate tests, yes, and one variable at a time wherever practical," Nathan said as he pulled one of the sheets closer. "If you alter six things and gain five horsepower, you've learned very little except that somewhere among six changes something happened."
"You really did spend two weeks reading," Mallory muttered, the irritation in his voice undercut by reluctant amusement.
"I told you I would."
"I thought you meant enough to understand what we were telling you."
"I did."
"That was your mistake," T said from behind them, and when Mallory laughed Nathan looked over his shoulder at the black lenses.
"Useful."
"I thought so."
"Start it."
The apron changed character almost immediately as conversation gave way to procedure, fuel and cooling connections were checked, restraints inspected and instruments prepared while Nathan watched the men as carefully as he watched the machine. Habit could preserve wisdom long after the reason behind a procedure had been forgotten, but it could preserve nonsense with exactly the same loyalty, and Nathan had learned to pay attention whenever someone performed an action so automatically that he no longer appeared to remember why he was doing it.
"Farther back, Professor," Mallory called as the mechanic approached the propeller, motioning Nathan away from the stand with the casual authority of a man momentarily more concerned with keeping him alive than remembering who signed the Institute's accounts.
Nathan moved immediately, and when Harris glanced at him in mild surprise he smiled. "Mr Mallory knows more about this machine than I do, so enjoy the moment because I don't intend for it to last forever."
T's shoulders shifted with suppressed amusement while Mallory shook his head and returned his attention to the engine. The mechanic called clear, final confirmations followed and the propeller was pulled through until the first cylinder fired with an ugly report that cracked across the field, another caught behind it, then another, and suddenly the separate explosions found their rhythm. The two wooden blades ceased being recognisable objects and became a translucent disc, exhaust hammered against the cold air and the engine strained against the reinforced mounting with such violence that Nathan could feel the vibration through the soles of his boots.
Technical drawings did not communicate that violence. On paper everything became clean lines, dimensions and labels; here fuel and air entered a metal chamber, were deliberately exploded and drove a piston hard enough to turn a crankshaft, after which the machine repeated the process hundreds and thousands of times while surviving because every component had been designed to tolerate the abuse. Human beings had taken explosions and taught them timing, and Nathan found something rather beautiful in that.
Mallory advanced the throttle until the note deepened and Nathan could feel it against his chest, Harris bending toward the instruments while another engineer recorded temperatures and revolutions. Nathan followed the readings, watched the vibration at different speeds and eventually raised his voice above the engine to ask for the compression ratio. Harris shouted the figure back, and Nathan frowned before looking from the instruments to the engine itself.
"That's all?" he called, waiting until Harris looked toward him before adding, "That may not be optimal."
Mallory heard him. Even from several yards away Nathan could see the argument beginning behind the man's eyes.
The test continued until Mallory signalled for power to come down, whereupon the translucent propeller slowly resolved into visible arcs and then individual blades while the last few uneven combustions coughed themselves into silence. The engine began ticking softly as it cooled, hot metal contracting in the cold air, and Nathan waited until the propeller had stopped completely before approaching.
"You think the compression is too low," Mallory said as he removed his ear protection and came around the stand.
"I think I don't know," Nathan replied, leaning toward the recorded figures rather than the engine.
"You just said it wasn't optimal."
"No, I said it may not be optimal, which is a considerably different statement. What happens if we increase it?"
"Potentially greater thermal efficiency and more power if the fuel tolerates it," Harris answered, having apparently decided that Nathan's questions were now inevitable and might as well be met quickly.
"And if it doesn't?"
"Knock, excessive heat, damage."
"What fails first?"
Harris opened his mouth, hesitated and looked at Mallory.
"We don't know precisely," Mallory admitted after a moment, then caught Nathan's expression and added, "Not under every combination."
"There," Nathan said, tapping the edge of the sheet with one finger. "The question."
"And your proposal is to keep increasing it until we destroy the engine?" Mallory asked.
"If necessary."
Harris stared at him.
"Not this engine," Nathan added, and Harris laughed before he could stop himself. "Establish a baseline, alter compression in controlled increments where the design permits it, record fuel, ignition, temperature and power, then determine where improvement diminishes, where detonation begins and which component becomes limiting. If we require an engine we're prepared to sacrifice, get one."
"And when we break something?"
"We examine the break."
"And then?"
"Ask why."
T released a slow breath behind them, the sound suspiciously close to a laugh, while Mallory rubbed one hand across his jaw and looked at the engine as though Nathan had just introduced it to a rather unpleasant future.
"If the piston fails, that is information; if a valve burns, that is information; if a bearing fails first, that is information," Nathan continued. "And if the fuel begins detonating before the structure reaches its limit, perhaps the fuel is the limiting component."
"Fuel development is another programme entirely," Mallory said, then stopped almost before the final word left him.
Harris looked at him, T looked at him and Nathan simply waited.
"I heard it," Mallory muttered.
"Nothing is another problem merely because the filing cabinet says so," Nathan said, unable to prevent a faint smile. "If fuel prevents the engine improving, fuel has become part of the engine problem."
He left the drawings where they were and walked toward the engineless aircraft, forcing the others to follow if they wanted to continue arguing with him. Two weeks earlier he had looked at an aeroplane and seen an aeroplane; now he saw compromises layered upon compromises, each necessary for some reason and each demanding payment somewhere else. Struts existed because the structure required them and imposed resistance because the air did not care why they were necessary, wires provided strength and added drag, the radiator kept the engine alive while disturbing airflow, and the undercarriage was indispensable on the ground while becoming dead weight once the aircraft had left it.
"One hundred and fifty is not our target," Nathan said as he rested a hand lightly against the fuselage and looked along the aircraft's length.
"Then what is?" Harris asked.
"I don't know, and neither do you; that's the point. We determine how much power can be produced reliably, how efficiently the propeller converts that power into useful thrust and how much of that thrust is then spent overcoming resistance we can reduce."
"You're talking about redesigning the engine or the aircraft," Mallory said.
"Yes."
"Which one?"
"Yes."
Harris laughed again, but Nathan continued before the exchange could become a joke. "I don't care which department owns the problem because the aircraft doesn't know which department designed which part of it. If the engine produces power the propeller cannot use, that's our problem; if the propeller produces thrust the airframe cannot tolerate, that's our problem; if strengthening the airframe adds enough mass to destroy the advantage, that's our problem too. Stop handing limitations from one department to another as though moving the paperwork changes the machine."
"He's going to make us work in the same room, isn't he?" one of the airframe engineers asked T, who had wandered closer during the discussion.
"I've seen what happens when he discovers departments aren't speaking," T replied, turning his dark lenses toward the man. "I'd recommend surrender."
"Tomorrow I want a list of every assumption currently being treated as a fixed limitation," Nathan said, ignoring both of them.
"Every assumption?" Mallory repeated.
"Engine and airframe."
"That could be hundreds."
"Good."
"And then?"
"Then we start breaking them."
The phrase did not sound particularly important when Nathan said it, and he forgot about it almost immediately. Weeks later he would pass through the aviation workshop and discover somebody had written BREAK THE ASSUMPTION, NOT THE MACHINE in chalk above a bench, while another hand had added beneath it IF YOU BREAK THE MACHINE, FIND OUT WHY, but for now Harris merely looked toward the cooling engine and began working through the problem aloud.
"We could alter compression on the bench engine," he said, already reaching for the earlier figures. "Not dramatically at first, but enough to establish whether the change behaves as expected."
"Within reason," Mallory replied, then caught Nathan looking at him and sighed. "Yes, all right, we determine what reason actually means."
"Better."
"We'll need proper power measurements."
"Build what you need."
"Fuel samples too, and ignition settings for every run rather than assuming the previous setting remains appropriate."
"Speak to the chemical section."
"We should measure what the airscrew is actually producing as well," Harris added, looking from the engine toward the propeller. "Manufacturer's figures won't necessarily transfer perfectly to this installation."
"Now you're asking useful questions."
Nathan stepped away once the engineers began arguing among themselves, deliberately resisting the urge to direct everything himself. Mallory wanted a sacrificial bench engine, Harris wanted additional temperature measurements and one of the airframe men raised the radiator arrangement only to be reminded that they were supposed to be changing one thing at a time, which made Nathan smile as T came alongside him.
"You know what you've done," T said, the black armour giving nothing away while the amusement in his voice did all the necessary work.
"Encouraged research."
"You've given engineers permission to break expensive things."
"Under controlled conditions."
"That'll comfort the accounts department."
"Failure is cheaper here," Nathan said, watching the cooling engine as Mallory and Harris bent over the figures, and the humour left T's voice because he understood the rest without needing it explained. A connecting rod through a casing on the ground meant an engine destroyed and perhaps an engineer having a very bad afternoon; the same failure at altitude might mean a man. "Break it here, understand it here, then send it up."
T nodded and turned his attention toward an aircraft passing high beyond the perimeter, its engine reduced by distance to a faint mechanical hum. Aviation was young enough that some of the men beneath it could remember when powered flight itself had been treated as a wonder, yet the war had already transformed that wonder into an industry of scouts, fighters and bombers. Nathan's reading had repeatedly brought him back to machines such as the S.E.5a and the roughly two-hundred-horsepower class of engines associated with its development, not because he intended simply to copy them but because they demonstrated how quickly one improvement exposed another problem. More power demanded reliability, reliability demanded better manufacturing, cooling and materials, and greater speed altered what the propeller and airframe had to endure.
"Think they'll get past one hundred and fifty?" T asked, following the distant aircraft until it disappeared into the grey.
"Wrong question," Nathan replied, turning back toward Mallory's group. "The question isn't whether they can get past one hundred and fifty; the question is why they haven't already."
Mallory heard him and looked across the field with the expression of a man who had just realised Nathan intended to ruin several perfectly serviceable weeks of his life, but he returned to the drawings without complaint. Nathan and T remained long enough to see the first sequence of tests agreed upon, then started back toward the main compound with the engineers still arguing behind them, their voices gradually disappearing beneath the wind while the smell of hot oil followed Nathan farther than the sound.
The transition from aerodrome to Institute happened beneath their feet rather than at any clean division between one part of Nathan's day and another. Mud gave way to firmer paths, the smell of petrol weakened behind them and the timber workshops receded while the larger compound rose ahead, newer buildings occupying spaces Nathan could still remember as open ground. T remained beside him in the same black armour he had worn throughout the morning, guards and workers recognising the figure as they approached without ever seeing the man beneath it, and Nathan found himself thinking again about how effectively an identity could disappear when people were given a symbol in its place. To the Institute, T was black armour, dark lenses, a voice and a reputation; nobody there needed Joseph Taylor, and Joseph Taylor was safer because of it.
"You enjoyed that," Nathan said as they passed the first checkpoint and T returned the guard's acknowledgement with a slight movement of his head.
"The engine?"
"The engineers."
"I enjoy other people discovering what the lower floor already knows."
"That I'm irritating?"
"That why ruins weeks."
Nathan smiled as they continued into the secured surface building, where cold wind became warm stillness as the doors closed behind them and the smell of petrol lingering on Nathan's coat mixed with floor polish, disinfectant and the faint chemical odour drifting from a laboratory corridor. A clerk carrying files stepped aside while two technicians passed with a padded equipment case between them, and Nathan realised he recognised none of the three.
That happened more frequently now. The Institute had expanded so quickly that its surface compound no longer resembled the modest collection of structures Nathan remembered from its first year; laboratories required stores, stores required roads and offices, new work required clerks, technicians, guards and telephone lines, while the lower facility had grown into something much closer to what Nathan had originally demanded. Independent ventilation, drainage and power served isolation corridors and sterilisation rooms beneath them, fire sterilisation and drop barriers could divide sections, one primary entrance controlled ordinary movement and a separately lockable emergency route existed for precisely that purpose. Beneath all of it sat the final answer, a scuttle plan designed to destroy the structure inward if containment failed badly enough, with no exception for records, specimens or Nathan himself.
The forty-tonne primary door impressed visiting officials because people were easily impressed by visible weight, but Nathan considered the smaller systems more important. A huge door became meaningless if procedures around it were poor; ventilation mattered, waste mattered, protective layers mattered, and a guard refusing an improperly documented entry mattered because catastrophe rarely introduced itself as catastrophe. More often it began with a small permission given to convenience: only this once, probably safe, someone else checked.
Growth made those sentences easier to produce. Nathan did not need to know every clerk by name, yet he disliked the distance appearing between the people who created rules and those expected to obey them, between the scientist conducting an experiment and the worker who cleaned afterward. Large institutions produced phrases he hated: I thought somebody else had checked. That belongs to another department. We've always done it this way. The aerodrome had spent the morning teaching him the last one again, while the lower facility could not afford either of the first two.
"I'm doing the lower circuit again," T said as they approached the restricted junction, his pace changing almost imperceptibly now that they were entering the part of the Institute for which he carried direct responsibility.
"You did it this morning."
"I've been away three hours."
Nathan nodded because three hours was enough. A lock could develop a fault, a log could fail to reconcile and a scientist could decide that a rule which had seemed reasonable at breakfast had become inconvenient by lunch. "Second containment corridor had a delay in the southern barrier yesterday."
"I saw it."
"And?"
"Probably the relay."
Nathan stopped walking, and T managed one additional step before stopping as well, then slowly turned the dark lenses toward him.
"Probably?"
"You're enjoying this."
"A little."
"The report suggests the relay."
"Then you'll have no difficulty proving it."
T stared at him for another moment, undoubtedly remembering the previous hours of engineers being tortured with precisely the same principle, before inclining his head. "I'll find out why."
"Good."
The guard opened the controlled access and T stepped through before looking back as the heavy door began moving behind him. "Compression ratio."
Nathan frowned. "What about it?"
"You'll think about it all night."
"No."
"You will."
"I have other work."
"That has never stopped you thinking about three things at once."
"Go frighten the lower floor."
"I've been practising."
The door closed between them and Nathan waited long enough to hear the locking sequence complete before continuing with the remainder of his own work, dealing first with a materials request Mercer had returned covered in enough handwritten objections to make the original author regret submitting it and then with a laboratory asking permission to retain contaminated outer clothing from field work rather than destroy it according to established doctrine. Nathan read the second request twice, dipped his pen and wrote that if examination of contaminated clothing was required they could produce clothing specifically for the experiment under controlled conditions, because field contamination did not become a free specimen merely because somebody found it interesting. He hesitated before adding MOVE LESS OF IT, then passed the paper onward and imagined Mercer approving.
By the time Nathan left the Institute the sky had darkened enough to threaten proper rain, and the road toward The Knapp carried him away from laboratories, workshops and guards into countryside that still looked half asleep beneath the remains of winter. For the first few miles T proved irritatingly correct because Nathan found himself reconsidering the compression figure Harris had given him, then the likely limitations of fuel, ignition timing, temperature, cooling and mechanical stress, only to realise he was redesigning half the engine inside his own head after spending the morning telling everyone else not to change six things at once.
"Not tonight," he muttered, smiling when the empty motor car offered no argument.
The Knapp appeared through the trees with warm light beginning to show behind several windows, the house having changed less visibly than the Institute over the years despite government correspondence, ministers, specimens and certain doors now possessing locks no respectable country house had ever been designed to require. Mrs Hargreaves had somehow preserved the fact that it remained a home through all of that, although Nathan sometimes suspected she achieved it chiefly by refusing to be impressed by anything he did outside it.
"Tea?" Mrs Hargreaves asked the moment he came inside, intercepting him before he reached the stairs and looking first at his face, then at the coat carrying traces of aerodrome mud.
"Yes."
"Food?"
"No."
"You said that yesterday," she replied, folding her arms as Nathan put one foot on the first stair. "You then ate at half past eleven, which suggests the word no does not mean what you think it means."
"I remember."
"Clearly not well enough to learn anything from it."
"Tea and something small, then."
"Something resembling food, and not a biscuit you discover behind a book."
"I know what food is."
"I have accumulated evidence suggesting otherwise," Mrs Hargreaves said, stepping aside at last and leaving Nathan to continue upstairs before she decided to present that evidence in detail.
His office remained largely as he had left it, seven Hertfordshire ledgers occupying one side of the desk with cross-references tucked between them while several notebooks remained open and the cup of questionable old tea Nathan had found behind a stack of journals the previous evening had disappeared, proving Mrs Hargreaves had entered during his absence and discovered another reason to despair of him. Horsley's enclosure stood near the smaller table by the window, the rat asleep beneath his bedding or at least appearing to be, while his wooden puzzle waited nearby and a small intelligence crate sat beside Nathan's chair where someone had delivered it during the morning.
Nathan removed his coat, placed the aeronautical folder on the desk and looked at it long enough for compression, fuel, propeller efficiency and drag to begin arranging themselves inside his head again, then pushed it deliberately to the far side. "Not tonight," he murmured, and the bedding in Horsley's enclosure moved as a small head emerged.
"That wasn't an invitation," Nathan told him as Horsley came farther out rather than returning to sleep. "Go back to bed."
Horsley remained where he was, whiskers moving while he watched Nathan.
"Fine."
Nathan lifted the intelligence crate onto the desk and removed the lid, sorting the packets by geography and subject while Horsley watched from across the room. Britain, Germany, Italy, Russia, the United States, shipping and industry occupied most of the space, while several smaller collections resisted easy classification and Nathan placed those where he could reach them rather than forcing them into a category for the sake of neatness. Uncertainty was useful when honestly labelled, and the same was true of information.
He took a blank sheet, dipped his pen in the ink, positioned the page between the surrounding packets and wrote APRIL 1918 across the top before resting the pen lightly against his fingers and surveying the material. The summaries had begun as a convenience but were becoming something closer to a method because Nathan wanted events beside one another rather than trapped inside the filing systems that produced them. Reality did not know which cabinet human beings had assigned it; a military offensive could alter railway traffic, railway traffic could alter shipping, shipping could alter the movement of disease, and an outbreak might appear in a medical report while the explanation for its spread sat three offices away beneath transport records.
The British packet came first, with the formal establishment of the Royal Air Force on the first of April occupying several pages and catching Nathan's attention less for the ceremony than for what followed it. A new organisation could be created on paper quickly, but technical habits, procurement, personnel and research cultures did not combine merely because somebody changed the heading on official stationery. Nathan wrote 1 APRIL — ROYAL AIR FORCE, followed it with WATCH TECHNICAL ORGANISATION. RESEARCH. PROCUREMENT, then glanced toward the aeronautical folder and added INSTITUTE AVIATION SECTION — LIAISON ONLY AFTER RESULTS JUSTIFY ATTENTION. He wanted a machine that worked before he wanted anyone important admiring the promise of one.
Germany came next, and Nathan read the newer material concerning Operation Georgette before pulling earlier reports from Operation Michael and comparing them rather than trusting his memory. The renewed offensive in Flanders demonstrated that German offensive capacity remained substantial, but communications, railways and the disruption of command interested Nathan as much as territorial movement. He wrote 9 APRIL — OPERATION GEORGETTE. FLANDERS, added a note concerning communications and railway objectives, then found the line he had written after studying Michael: DECAPITATION WITHOUT DESTRUCTION. Hale had received the thought in a more useful form—COMMUNICATIONS REDUNDANCY. ASSUME DELIBERATE ISOLATION OF SECTIONS—because a containment facility was not an army, but systems shared vulnerabilities.
Nathan began writing what he believed the German command intended, stopped halfway through the sentence and marked it separately as interpretation rather than established fact. He disliked making that distinction most when he felt certain, which was precisely when it mattered.
The faint click of wood against wood came from Horsley's table, and when Nathan looked across the room he found the rat already nosing at the puzzle.
"You were asleep," Nathan said, watching Horsley work at one of the sliding pieces before returning to Rome.
The Congress and Pact material interested him because of what it suggested about Austro-Hungarian political cohesion, an empire being a structure held together by far more than armies: administration, force, legitimacy, habit, agreement and enough people continuing to behave as though the structure would still exist tomorrow. Nathan wrote ROME — PACT OF ROME, followed it with POLITICAL COHESION RELEVANT ALONGSIDE MILITARY CONDITION, and deliberately avoided writing collapse. Structures could rot for years without falling when observers expected them to, and biology had taught Nathan not to call anything dead while it was still moving.
Russia followed, then Japan, Vladivostok, American production and shipping, Nathan reading nonlinearly and repeatedly returning to earlier documents whenever something later changed their meaning. Railway memoranda sat beside military movements, while industrial figures ceased being abstract tonnes and production totals once Nathan began thinking about what armies actually required behind the front. Rifles required metal, machinery, trained workers, gauges, timber, packing, railways, ports and ships; ammunition consumed that chain continuously, as did food, medicine, boots, horses, engines, spare parts and dressings. The battlefield was merely where the chain ended, while the war extended much farther.
"More engines?" Mrs Hargreaves asked as she entered carrying tea and a plate containing considerably more than Nathan considered something small, her eyes travelling over the papers before settling on the abandoned aeronautical folder.
"Later," Nathan replied, taking the cup when she placed it beside him and drinking before she could order him to.
"That sounds dangerous."
"Why?"
"You only say later when something else has occupied you."
"That isn't true."
Mrs Hargreaves said nothing, simply looking at him with the patience of someone prepared to wait until the lie became embarrassed enough to leave on its own.
"Occasionally," Nathan conceded.
"Mm. Eat something as well."
Nathan took a piece from the plate, bit into it and raised his eyebrows. "Remarkable."
"I thought so."
Mrs Hargreaves turned toward the door just as Nathan opened the next packet and saw the heading UNITED STATES — KANSAS. Something in the first page changed the way he held himself, not dramatically enough that anyone unfamiliar with him would have noticed, but Mrs Hargreaves had been familiar with him for years and stopped before reaching the doorway.
"What is it?" she asked, remaining where she was while Nathan continued reading.
Camp Funston. Fort Riley. March. More than a hundred soldiers reporting sick within a short period with an influenza-like respiratory illness. That alone was not extraordinary because military camps were excellent places for respiratory disease; young men arrived from different communities, lived in close quarters, trained together, ate together and breathed the same enclosed air before moving elsewhere in groups, and Nathan would have been more surprised if such places never produced outbreaks. He turned the page expecting routine uncertainty and instead found the Institute memorandum attached behind the report.
Available British information was inadequate. Clinical descriptions varied. Preserved material was insufficient or absent. Secondary pneumonia complicated some cases, and terminology used by different physicians was inconsistent enough that the Institute could not determine whether the reports described familiar influenza, several respiratory illnesses grouped beneath the same convenient name or something not yet properly characterised.
At the bottom of the memorandum someone had written a single word.
UNDETERMINED.
Nathan read it twice, not because the word suggested anything extraordinary but because it refused to. Somebody had reached the edge of the evidence and stopped, which was harder than it sounded; Nathan had known physicians, scientists and military men who could turn possibly into probably during one conversation and probably into certainly by the time a report reached the next desk. Undetermined meant the writer possessed enough discipline to admit ignorance, and Nathan valued that considerably more than a confident guess.
"A sickness," he answered at last, drawing the first report closer and reading it again.
"Where?"
"Kansas. The Institute has been trying to determine what caused an outbreak among soldiers there and hasn't been able to."
"Is it dangerous?" Mrs Hargreaves asked, coming back toward the desk while Nathan turned from the symptoms to the movement records.
"I don't know," Nathan replied, touching one finger against UNDETERMINED before tracing the paperwork beneath it. "That is the problem."
Men arrived at camps and men left them. Trains connected those camps to ports, ports connected to troopships, troopships connected America to Europe, and European ports fed depots, hospitals, railway stations, camps and eventually the front. Nathan pulled several European respiratory reports from another packet and spread them beside Kansas, careful not to grant them a relationship merely because they now occupied the same desk. A cough in France did not become connected to Kansas because Nathan wanted an interesting answer; influenza existed without mystery, pneumonia existed without conspiracy and two ordinary outbreaks could resemble each other because ordinary disease was perfectly capable of repetition. Movement existed too, however, and that was enough to justify a question.
He drew his April chronology closer, dipped the pen in the ink and wrote MARCH–APRIL — KANSAS. RESPIRATORY OUTBREAK. CAUSE UNDETERMINED, leaving the final words unadorned rather than underlining them as though typography might make ignorance more dramatic.
"Pack my luggage," Nathan said, keeping his eyes on the movement records while Mrs Hargreaves stared at him.
"When?"
"Now."
"Where are you going?"
"America."
There was a brief silence in which Nathan continued reading and Mrs Hargreaves apparently considered several responses before selecting the least insulting. "Where in America?"
"Kansas."
"Kansas," she repeated, moving around the edge of the desk until she could see the report. "In the middle of a war."
"The war isn't in Kansas."
"The ocean between here and Kansas is participating."
"That is true," Nathan admitted, looking up at her at last.
"I am pleased we've established it."
"We'll arrange proper passage."
"How long?"
"I don't know."
"That answer is becoming very irritating."
Nathan found a clean sheet, dipped his pen, positioned it beside the Kansas packet and began writing while he spoke. "Send this to Hale. I'm leaving Britain, his authority remains unchanged, there is to be no relaxation of access because I'm absent and no security decision waits for my return. Willit is to collect everything concerning respiratory illness among American and European troops, including reports previously dismissed as routine or unrelated; I want onset dates, locations, unit movements, hospital admissions, deaths, recoveries and every diagnosis that changed after initial examination."
Mrs Hargreaves listened while he filled the first page and moved immediately to another.
"If preserved samples exist, I want to know where and under what conditions; if they don't, I want to know why, and Willit should request material ahead of us before anyone disposes of it as ordinary hospital waste. Observation and interpretation remain separate. Nobody is to decide two outbreaks are connected because the symptoms sound alike, and nobody is to decide they're unrelated merely because one happened in Kansas and another in France."
"And T?" Mrs Hargreaves asked when Nathan finished, taking the folded instructions from him and glancing at the recipients.
"Tell him to pack; we're going to Kansas."
"Does he know?"
"He will when you tell him."
"You haven't asked him."
"No."
Mrs Hargreaves lowered the paper and stared at Nathan. "You are sending me to inform an armed man dressed head to foot in black armour that he is crossing the Atlantic."
"He'll be delighted."
"I have met T."
"He likes travelling."
"I have never heard him say that."
"He went to Africa."
"With you."
"Exactly."
"That is not evidence of enjoyment," she replied, folding the message with the careful precision of someone preventing herself from doing something less dignified with it, then turning toward the door.
"Mrs Hargreaves," Nathan said before she reached it, originally intending only to tell her to pack warm clothing, but when she looked back he found himself noticing things he had not intended to notice at all.
She had looked after The Knapp for years, although somewhere along the way looked after The Knapp had ceased being an adequate description of what she did. She looked after Nathan too, ensuring he ate when work made ordinary hours meaningless, knowing which visitors could interrupt him and which could wait, understanding where government correspondence belonged and which packages could be opened without asking. She complained about muddy boots, leaking crates, abandoned cups and ministers arriving late with exactly the same authority she had possessed before there were ministers arriving at all, and she had known Nathan before the Institute grew into something with lower levels, forty-tonne doors, Cabinet meetings and black-armoured guards. Through every alteration she had retained the useful habit of treating Nathan Drake as Nathan Drake rather than the founder or director of anything.
There was more grey in her hair now than when he had first known her, and fine lines had gathered around her eyes while the years had altered Nathan so little that the difference between them was becoming increasingly difficult not to notice. He had spent enough time thinking about death to understand its horror, but increasingly he suspected ordinary people underestimated the strangeness of the alternative. Years changed the people around him, and he remained.
"What?" Mrs Hargreaves asked when his silence became noticeable.
"Why don't you come with us?" Nathan said, watching confusion appear before he clarified, "To America."
"You want me to go to America."
"Yes."
"Why?"
"Because you've never been."
"Neither have most people."
"Neither have I, properly."
"You are going to investigate an unidentified sickness."
"You don't have to investigate it," Nathan replied, unable to keep a small smile from his face when her expression became even less impressed.
"That is enormously comforting."
"I'm serious. You've spent years here while I go everywhere else—London, France, Africa, Birmingham, wherever someone sends me a letter containing a problem interesting enough to ruin the week. Come with us and see somewhere new."
"Someone has to look after this house."
"The house will survive."
Mrs Hargreaves raised her eyebrows.
Nathan considered the statement more carefully. "Probably."
"That is exactly what concerns me."
"We'll leave someone responsible."
"You?"
"No."
"Good. For a moment I thought the illness had already reached Hertfordshire."
Nathan laughed, and Mrs Hargreaves's mouth threatened to move before she controlled it.
"I am capable of seeing somewhere different without accompanying you toward an epidemic," she said.
"Then don't accompany me into hospitals. T and I can handle that; stay where we're lodging when necessary, and if we pass through New York, see New York. See the country on the journey west. America is large, and I imagine some of it isn't diseased."
"You imagine."
"I haven't checked."
This time she did smile, although only briefly. "The Atlantic remains full of German submarines."
"I'll arrange proper passage."
"There is that phrase."
"What phrase?"
"I'll arrange it. You say it immediately before causing somebody else a great deal of work."
"Yet here you are."
"Against all probability."
"Come with us," Nathan said again, the humour leaving his voice because he wanted her to understand that beneath all his practical arguments there was no hidden necessity. He simply wanted her there.
Mrs Hargreaves looked at him for several seconds and apparently understood, because some of the resistance left her expression even though the dryness remained. "If I am expected to keep both of you alive in another country, I shall need more than five minutes to pack."
"That means yes?"
"It means I am considering the catastrophic consequences of leaving this house unsupervised."
"That sounds like yes."
"It sounds like you should not push your luck."
Nathan smiled.
"And if I go, I am not spending the entire journey sitting in hotels while you and T disappear for twelve hours."
"You said you wanted to see America."
"I did not."
"You implied it."
"I did no such thing."
"You're learning from me."
"God forbid."
"Warm clothing," Nathan said as she turned once more toward the door.
"For Kansas?"
"And possibly France first."
Mrs Hargreaves stopped with her hand halfway toward the handle and slowly looked back. "France."
"I want to determine whether the respiratory illness being reported among troops there resembles the American cases before we cross the Atlantic; if it does, the chronology matters, and if it doesn't, that matters too."
"Of course you do," she muttered, closing her eyes for a moment before opening them again. "I suppose merely travelling to America would have been too straightforward."
"It makes sense."
"I am sure it does to you."
"It should to everyone."
"That is generally when I become concerned."
"One more thing."
"There always is."
Nathan looked toward Horsley's enclosure, where the rat had abandoned the puzzle and now sat cleaning one forepaw. "Have a travelling carrier made for Horsley, secure and ventilated, large enough that he isn't confined in a tiny box for the entire crossing, with a covered section for bedding and separate space for food and water. It should have fixing points so it can be secured in the cabin if the ship moves badly, and make certain the catches are sound."
"You're taking the rat," Mrs Hargreaves said, following his gaze before turning back to him.
"Horsley."
"I know his name, Nathan. I am objecting to the rat, not suffering a lapse of memory."
"I'm not leaving him here for an indeterminate period, and I have observations I intend to continue while we're away."
"What sort of observations?"
"Mine."
Mrs Hargreaves stared at him.
Nathan stared back.
"That answer generally means I am better off not asking twice," she said eventually.
"Frequently."
"You invited me to America before mentioning that I would be travelling with a rat."
"I didn't think it would affect your answer."
"It might have improved the accuracy of it."
"He won't be your responsibility."
"You say that now."
"I feed him regularly."
Mrs Hargreaves looked deliberately at the plate beside Nathan, most of its contents untouched.
Nathan followed her gaze. "That is different."
"I am fascinated to learn how."
"He cannot open a cupboard."
"Apparently neither can you."
Nathan took another piece of food from the plate and ate it while maintaining eye contact, earning the smallest possible nod of approval.
"The catches still need to be good," Nathan continued once he had swallowed. "Rats are better at exploiting poor construction than people give them credit for, and I don't want to spend part of an Atlantic crossing removing him from somewhere inside a ship."
"Has he escaped before?"
"No."
"Then why are we building his carrier as though he has?"
"Because I'd prefer to preserve that record."
Mrs Hargreaves looked toward Horsley, who had finished cleaning himself and was now nosing around the edge of his enclosure with every appearance of being nothing more remarkable than an inquisitive rat. She knew Nathan used him for some manner of research because Nathan had never pretended otherwise, but she had neither the details nor the inclination to pry into every experiment conducted beneath her roof, particularly when Nathan's answers became shorter the closer she approached something he regarded as private.
"So," she said, counting the accumulating inconvenience on her fingers, "warm clothing, your luggage, my luggage apparently, T, France, America, Kansas, an unidentified illness and a secure travelling box for Horsley."
"Carrier."
She looked at him.
"Box is acceptable."
"Anything else?"
Nathan thought.
Mrs Hargreaves pointed at him before he could speak. "Do not."
"I wasn't going to say anything."
"You were thinking."
"I frequently do."
"Try less of it until I've reached the stairs."
She left before Nathan could answer, her footsteps crossing the landing and beginning down before stopping abruptly.
"Mr Drake!"
Nathan leaned back in his chair. "Yes?"
"Does the rat require travel papers?"
Nathan opened his mouth, then stopped because the question was irritatingly legitimate. He looked toward Horsley, who offered no assistance whatsoever. "I'll find out."
"Of course you will."
Her footsteps continued downstairs while Nathan remained still for several seconds before laughing quietly and turning toward the enclosure. "This is your fault."
Horsley returned to his puzzle.
The house changed around Nathan almost immediately, Mrs Hargreaves's voice carrying faintly through the lower hall as staff were summoned, cases discussed and somebody instructed to find out whether a carpenter could be brought before evening. Nathan returned to the Kansas reports while those domestic preparations blended with the work already moving outward through the telephone, the journey becoming real not through any single dramatic decision but through a dozen practical ones made by people who understood that crossing an ocean required rather more than Nathan deciding he wanted to look at something.
He returned to the movement records and found himself increasingly bothered less by the symptoms than by the routes. The war had spent years gathering human beings together on a scale difficult to comprehend, drawing men from farms, villages, towns and cities into camps before feeding them through railway stations and ports, putting them aboard ships, carrying them across oceans and redistributing them through another network of railways, depots, hospitals and front-line formations. A body moved blood through vessels, the war moved men through routes, and anything travelling inside those men inherited the routes without needing to understand them.
Nathan wrote DO NOT CONFUSE FIRST RECOGNISED OUTBREAK WITH ORIGIN, then added MAP CASES BY DATE AND MOVEMENT, NOT MERELY NATIONALITY OR DIAGNOSIS before stopping to consider the figures again. A hundred sick soldiers sounded dramatic until somebody asked a hundred out of how many, so he added questions concerning the number exposed who did not become ill, barracks distribution, sleeping arrangements, duties, recent arrivals and recent departures. The first recognised patient was not necessarily the first infected person, and the first recognised outbreak was not necessarily the origin; human beings liked beginnings because beginnings made stories cleaner, but biology rarely cooperated.
"You haven't eaten," Mrs Hargreaves said when she returned, carrying the folded copies of his messages and stopping beside the desk when she saw the plate.
"I have."
"One piece."
"Two."
"That does not improve your defence as much as you think."
Nathan took another and ate it while she watched. "Three."
"Remarkable."
"I thought so."
A wooden click sounded from across the room, and Nathan's attention shifted immediately toward Horsley, who had moved part of the puzzle aside and reached the small reward concealed beneath it.
"That was quicker," Nathan murmured, rising from his chair and crossing the room while Mrs Hargreaves remained beside the desk.
"You give him that thing often enough," she said, watching Nathan reset the pieces, "and eventually even a rat ought to remember where the food is."
"Perhaps."
Mrs Hargreaves heard nothing unusual in the answer and turned back to the messages, while Nathan altered one part of the mechanism before setting the puzzle down again. Horsley approached where the previous solution had begun, encountered the changed arrangement and stopped, his nose moving rapidly before he shifted to another side.
Nathan watched without comment.
Memory of a sequence was one thing. Recognising that the sequence no longer produced the expected result and abandoning it in favour of another approach was something else, but Mrs Hargreaves had no reason to know that distinction mattered and Nathan had every reason to keep it that way.
"The message for T has gone," she said as Nathan returned to the desk. "Hale's as well."
"Good."
"Your carpenter is expected before supper."
"Excellent."
"You will not turn a rat box into a laboratory."
Nathan looked at her.
"That look means you were already planning to."
"I need it to be secure."
"You need it to contain one rat between here and America."
"Precisely."
Mrs Hargreaves sighed and left him to it.
The carpenter arrived before dark, and Nathan made a sincere attempt not to turn Horsley's carrier into an engineering programme, although the attempt deteriorated once his original requirements expanded to reinforced edges, protected ventilation, two reliable catches, a removable tray, padding sufficient to reduce vibration and fixing points that would allow the enclosure to be secured during rough weather. Nathan wanted part of the carrier capable of being covered so Horsley could retreat from crowds and noise while the remainder retained sufficient airflow, and when the carpenter produced a suggested latch Nathan tested it twice before shaking his head.
"Too easy to knock loose."
"By the animal?"
"By anyone carrying it."
The carpenter replaced it with another from his case, and Nathan tested that one before nodding.
"Particular about him, aren't you?" the man asked as he measured the dimensions of Horsley's existing enclosure.
"I prefer not to lose experimental animals."
"Fair enough."
Horsley came toward the side of the enclosure nearest the unfamiliar man, sniffed at the air and then wandered away again, which earned him no more than a passing glance. To the carpenter he was a brown rat kept by a scientist who apparently possessed more money than sense when it came to transport boxes, and Nathan was perfectly content to leave that impression intact.
"You could buy another rat in America," the carpenter said while writing down the final measurements.
"Not this rat."
The man looked at him, apparently decided that scientists became attached to stranger things and returned to his measurements without another question.
Rain had begun against the windows by the time he left, and Nathan returned to his office where Kansas and the European reports waited exactly as he had left them. He placed dates beside one another without drawing lines between them, because that mattered; a line connecting two events would imply a relationship he did not yet possess. Possibility was not connection, connection was not causation and similarity was not identity, principles Nathan found himself repeating more often since Africa because encountering something genuinely extraordinary created its own intellectual danger. Once a man discovered that monsters existed, every shadow became more persuasive. The Ndipaya flower had been real and the things associated with it had been real, but that did not make every unexplained disease another Ndipaya, nor did a strange report from Russia automatically belong beside Kansas simply because Nathan could not immediately explain either one.
Mystery was intoxicating, which made discipline more important after the world had given you reason to believe in monsters.
"Drake," Nathan said when the telephone rang, reaching it before Mrs Hargreaves could come upstairs and listening as Willit explained that the medical section had already found respiratory reports from France filed beneath several different descriptions. Influenza appeared repeatedly, but so did pneumonia and other less consistent terminology, and when Willit suggested standardising the entries Nathan stopped him before the idea could become practice. "Preserve the original language. You may create a separate standardised field if you need one, but keep what the physician actually wrote because I want to know what they believed they were seeing at the time, not what we decide three months later that they ought to have called it."
Willit answered, and Nathan drew a notebook closer.
"Yes, movement records as well."
Another answer followed, this one apparently concerning the scale of what Nathan had requested.
"I know that could be hundreds; get another clerk."
Nathan listened, smiled and leaned back in the chair. "No, you may not blame me when the filing room runs out of space."
Willit said something else.
"You already do? Good, then nothing changes."
Nathan hung up and discovered Mrs Hargreaves standing in the doorway.
"How many people's evenings have you ruined?" she asked, one hand resting against the frame.
"Only several."
"It's early."
She disappeared again before Nathan could answer.
The telephone was still warm beneath Nathan's hand when, miles away beneath the Institute, a runner reached the southern barrier and found T standing beside an opened relay housing while an electrician worked with one arm inside it. T had remained in the same black armour he had worn at the aerodrome, his identity as inaccessible to the men around him as it had been beneath the open sky, and when the runner offered him the folded note he read it without moving anything except his head.
"Problem?" the electrician asked after T had remained silent for several seconds.
"This morning I was looking at an aeroplane engine," T replied, folding the note and putting it away while the electrician withdrew his hand from the relay. "Now I'm going to Kansas."
"Kansas?"
"America."
The electrician blinked. "I am aware where Kansas is."
"Then you're already better prepared than I was five seconds ago."
The man beside the barrier laughed before thinking better of it, while T looked back toward the open relay housing. "And this?"
"Looks like the relay."
The dark lenses turned toward him.
The electrician closed his eyes briefly. "I'll find out why."
"Everyone's learning," T said, and resumed the circuit without yet knowing that the journey to Kansas had acquired Mrs Hargreaves and a rat.
By the following morning the first French material was sufficient to settle the question of the detour. France first, not because Nathan had established a connection but because he had not. He wanted physicians who had seen the cases directly and nurses as well, because nurses often remembered the progression of an illness more clearly than physicians who passed through once or twice a day. He wanted original notes, preserved material if any existed, autopsy findings where deaths had occurred, barracks arrangements, onset dates and movements, but most importantly he wanted to ask what had seemed ordinary before asking what had seemed strange. If Nathan arrived announcing that he was investigating an extraordinary disease, people would give him extraordinary stories; human beings were helpful that way.
Willit's section had commandeered a room by the time Nathan returned to the Institute, clerks working beneath stacks of hospital summaries while maps covered part of one wall and pins had begun appearing across France. Nathan disliked the pins almost immediately, not because they were useless but because they looked more meaningful than the information behind them deserved.
"Don't interpret density yet," Nathan said as he entered, stopping several feet from the map.
"I already told them," Willit replied without looking up from the file in his hands.
"A cluster could mean disease or it could mean one physician writes better reports than everyone around him."
"I know."
Nathan glanced at him and saw exhaustion in the man's face, approving of the work but not the exhaustion.
"Respiratory illness is everywhere if we define it broadly enough," Willit continued, setting one file down and selecting another. "That is the first problem. Influenza, pneumonia, bronchitis, catarrhal fever, fever with respiratory symptoms and cases without useful descriptions at all; some hospitals record onset, others record admission and leave us to guess the rest."
"Don't guess."
"I wasn't planning to."
"Good."
Willit gave him a tired look and handed over a sheet. "We have enough from France to justify looking in person."
Nathan read it slowly. Several clusters, some mild, some complicated by pneumonia, timing uncertain and connections uncertain. Exactly as expected.
"Preserved samples?"
"Very little."
"Autopsy material?"
"Possibly."
Nathan looked up.
Willit closed his eyes. "I knew you were going to do that."
"Do what?"
"Say possibly like that."
"If possibly is accurate, possibly is fine."
"I haven't confirmed whether the material still exists."
"Then find out."
"I am."
"Good."
Willit watched him return to the report before asking, "You're going to France, then?"
"Yes."
"And then Kansas?"
"Yes."
"T?"
"Yes."
Willit hesitated long enough for Nathan to notice.
"What?"
"Mrs Hargreaves?"
"Yes."
Willit stared.
Nathan turned the page. "And Horsley."
There was a silence long enough that one of the clerks stopped turning pages.
"The rat," Willit said.
"Yes."
Another pause followed, and Nathan looked up at last. "Something wrong?"
"No."
"Good."
The clerk resumed turning pages with extraordinary concentration. Willit knew Horsley existed because a rat kept by the Institute's director was difficult to conceal indefinitely, but Nathan had never given him the experimental records, never explained what had been introduced into the animal or what Nathan was attempting to produce, and Willit possessed enough experience with restricted work to understand that an unanswered question sometimes remained unanswered because the person with authority over it intended precisely that.
Hale's objections began before noon, although most were less objections to the journey itself than to Nathan's irritating habit of announcing journeys before allowing security to determine how they were actually possible. Shipping during wartime was not a matter of buying tickets and arriving at a port with luggage; travel had to be legitimate enough to survive inspection, secure enough for Nathan's purposes and inconspicuous enough not to advertise the Institute. T created a separate problem because within Institute ground he remained T, fully armoured and anonymous, whereas beyond it he could not simply walk through civilian ports looking like the black figure half the Institute associated with restricted corridors. Hale therefore arranged the transition away from Institute observation, ensuring nobody employed there would see Joseph Taylor emerge from T's armour and nobody outside would have reason to know T existed. Travel documentation, clothing and movement could conceal the man by making him ordinary rather than making him visibly secret.
"You're taking Hargreaves," Hale said once the more serious matters had been covered, lowering the travel papers and looking at Nathan as though he suspected some detail had been omitted.
"Yes."
"Why?"
"Because I invited her."
Hale stared. "That wasn't a security reason."
"No."
The admission appeared to unsettle him more than an argument would have.
"She stays away from restricted medical environments unless there is a reason otherwise," Nathan added.
"That helps."
"Horsley is coming too."
Hale closed his eyes.
Nathan waited.
"The rat."
"Yes."
"Why?"
"Because I'm not leaving him here."
Hale opened his eyes again. "That is not a security reason either."
"No."
"What exactly am I expected to put on the paperwork?"
"A rat."
"I had reached that conclusion myself."
Nathan smiled. "Mrs Hargreaves asked whether he needs travel papers."
Hale's expression became perfectly still.
"I told her I'd find out."
"I'll find out," Hale said, reaching for another sheet before Nathan could continue, then pointing at him when he saw the beginning of a smile. "Don't."
"I didn't say anything."
"You were going to."
"I was thinking."
"Go bother Willit."
Nathan laughed and left him to it, privately satisfied that neither Hale nor Mrs Hargreaves had asked the question Nathan had no intention of answering: why Horsley, specifically, mattered enough to transport across an ocean during wartime.
T found him later that afternoon, still dressed in the same black armour he had worn at the aerodrome because there was no reason for him to be anything else while inside the Institute, and closed Nathan's office door before standing silently on the other side of it.
"You're taking the rat," T said after several seconds, his dark lenses fixed upon Nathan while Nathan continued reading.
"Yes."
"To Kansas."
"Yes."
"On a ship."
"Yes."
T waited, and Nathan eventually looked up. "Is there a question?"
"Hargreaves too."
"Yes."
"You asked her?"
"Yes."
The humour that had been present in T's voice disappeared so subtly Nathan almost missed it. "You ask people to come with you when you expect to come back," he said, leaning one shoulder lightly against the wall while Nathan lowered the report. "Africa wasn't like that."
"No," Nathan replied.
"This isn't Africa."
"No."
"You don't know what Kansas is."
Nathan looked down at UNDETERMINED on the report between his hands. "No."
"That is why we're going."
T nodded once, and when he spoke again the humour had returned. "So the rat has a cabin?"
"No."
"Good. I was going to object if Horsley travelled better than I did."
"He has a custom carrier."
T stared at him.
Nathan waited.
"Of course he does."
"Mrs Hargreaves calls it a box."
"She's right."
Nathan smiled as T pushed himself away from the wall.
"When?"
"France first, then America."
"Warm clothing?"
"Yes."
"Anything else?"
Nathan considered.
"Careful," T warned, raising one gloved finger.
"Mrs Hargreaves did exactly that."
"I learn from professionals."
T reached the door before looking back. "Do we know what we're looking for?"
"No."
"Good."
Nathan frowned. "Good?"
"Means you won't tell me you've already solved it before we arrive."
Nathan picked up a pencil.
T closed the door before he could throw it, and the pencil struck the wood hard enough to make Nathan stare at it for a moment before smiling and returning to his report.
The carrier arrived at The Knapp unfinished that evening for inspection, and Nathan placed Horsley inside long enough to see what he investigated first. The rat moved around the unfamiliar space with his nose close to the timber, sniffed at the corners, rose briefly against the mesh and eventually came to the door, where his forepaws rested against the lower frame while his whiskers worked furiously.
"He's found the way out already," Mrs Hargreaves said, standing beside Nathan while the carpenter inspected the opposite side.
"He's found the door."
"That is usually where the way out is."
Nathan glanced at her, then crouched and pressed one finger against the lower edge of the frame. "Reinforce this section. It will take more wear than the others."
"From him?" the carpenter asked.
"From opening and closing it."
The answer came easily enough that neither man nor housekeeper had reason to hear anything concealed inside it, and Nathan kept watching as Horsley moved away from the door and began investigating the covered section.
"Seems settled enough," the carpenter said.
"He'll do."
"You've gone to considerable trouble for one rat," Mrs Hargreaves remarked as Nathan checked the fixing points.
"I've gone to considerable trouble to avoid chasing one rat around a ship."
"That explanation I believe."
"I'm glad."
The following days tightened around the journey as Willit's packet became two packets and then a locked case, Hale turned vague intentions into routes, checks and contingencies, and Mallory sent Nathan the first baseline results from the aviation section with a note stating that controlled compression trials would begin as soon as the instrumentation was satisfactory. Nathan wrote DEFINE SATISFACTORY beneath it and sent the paper back, only for Mallory's reply to arrive several hours later bearing the words WE ARE DETERMINING WHAT IT MEANS in handwriting considerably larger than necessary.
Nathan kept the note.
The Institute continued working without him, which mattered more than he expected. There had been a time when Nathan could picture almost every occupied room at night, knew which researchers remained at their benches and which guards made which circuits, but that Institute was gone. The new one breathed without him. Hale could run security, Willit could run his section, Mercer could run his, T did not need Nathan standing behind him and Mallory's engineers were already learning to question their own limits. Nathan had wanted this growth, yet he was not entirely certain he liked the distance it created, although an institution incapable of functioning when its founder left the room was not an institution at all. It was a dependency.
On the final evening before departure Nathan sat again in his office at The Knapp with the April chronology before him, the page now crowded with entries running from the creation of the Royal Air Force to Operation Georgette, Rome, Russia, Japan, Vladivostok, American production and shipping, until his eyes settled once more upon MARCH–APRIL — KANSAS. RESPIRATORY OUTBREAK. CAUSE UNDETERMINED. Horsley's finished carrier stood near the wall with bedding and supplies not yet placed inside, while the rat remained in his familiar enclosure for one final night, Mrs Hargreaves's luggage waited downstairs and somewhere beyond the house T's arrangements were already complete.
A house preparing for absence possessed a sound of its own, quieter in some places and busier in others. Cases closed downstairs, instructions were repeated, doors checked earlier than usual and Mrs Hargreaves had spent the day behaving as though leaving The Knapp in somebody else's hands constituted a moral failure she had reluctantly agreed to commit. Nathan listened to those sounds while looking at Kansas and found himself thinking about the different ways important things announced themselves.
An air force could be created and newspapers could print the name, an army could attack and artillery announce it across miles, delegates could meet and publish declarations, but disease required none of those things. It needed proximity, a lung and then another lung, while a barracks helped, a railway carriage helped more, and ports, troopships, depots and camps did the rest without ever knowing they had participated. The war had constructed one of the largest systems for moving human beings the world had ever seen, and any organism capable of travelling inside those human beings would inherit that system without understanding that the system existed.
That disturbed Nathan more than the Kansas report itself, not because it proved Kansas mattered—it did not—but because if Kansas mattered, the infrastructure required to make it matter elsewhere already existed. A railway did not care why a passenger travelled, a ship did not distinguish a soldier's lungs from cargo and an organism did not need to understand borders in order to cross them.
Nathan drew the European reports closer, compared a date in France with a hospital admission, troop movement and ship departure, then placed a small mark beside two entries without drawing the line his mind wanted to draw between them. A line would suggest connection, and he did not have one yet. Possibility remained possibility, exactly where it belonged.
A faint wooden movement came from Horsley's enclosure, and Nathan glanced across in time to see the rat reach the end of the puzzle and expose the food beneath the final piece. He checked the clock before rising, reset the mechanism with one section moved into a different position and placed it back without comment, watching as Horsley approached the familiar object and began where the previous solution had worked. When that route failed, the rat paused, shifted his weight and moved around the puzzle before trying another section.
Nathan's attention sharpened.
He said nothing.
Horsley worked again, abandoning the failed sequence more quickly on the second attempt, and Nathan crouched beside the table with his forearms resting loosely against his knees. Nobody else knew what had been done to the animal, and Nathan intended to preserve that ignorance. To Mrs Hargreaves, Horsley was a rat Nathan used for some private experiment and had become peculiarly attached to; to Hale he was an inconvenient item requiring transport arrangements; to Willit he was one of Nathan's restricted projects, which was enough information for a man accustomed to compartmentalisation. None of them knew about the minute Red-Light material Nathan had introduced, the alterations he had encouraged or the reason a rat remembering a wooden puzzle mattered more than it appeared to.
That knowledge belonged to Nathan.
Horsley solved the altered section.
Nathan reached for the notebook he kept separately from the ordinary records and wrote the time before recording the configuration, the failed initial sequence and the change in approach, his handwriting becoming smaller as the observation grew more detailed. He did not write understands, because understanding was a conclusion and behaviour was evidence; he wrote what Horsley had done, what had changed and what Nathan would alter during the next trial.
"You're becoming difficult," Nathan murmured, closing the notebook before returning the puzzle to its starting position.
Horsley looked toward his hands.
Nathan stopped.
The rat remained still.
Slowly, Nathan moved one section while allowing Horsley an unobstructed view, then obscured the remainder with his other hand before changing a second part. When he withdrew, Horsley approached the section he had watched Nathan alter first.
Nathan felt the quiet thrill of a question opening.
"You saw that."
Horsley continued working.
Nathan repeated the trial with a different arrangement, this time preventing the rat from seeing the reset at all, and the change in Horsley's behaviour was small enough that anyone passing the doorway might have seen nothing beyond an animal nosing around a wooden object in search of food. Nathan saw considerably more, but he refused to give the observation a meaning it had not yet earned.
He returned to the notebook and wrote POSSIBLE USE OF VISUAL INFORMATION DURING RESET. REPEAT UNDER CONTROLLED CONDITIONS. DO NOT INFER COMPREHENSION FROM SINGLE TRIAL, then closed it as footsteps approached along the landing.
"You haven't eaten," Mrs Hargreaves said as she entered, looking toward the plate on Nathan's desk rather than the puzzle beside him.
"I have."
"Not enough."
"I'll eat before bed."
"You said that yesterday."
"I eventually did."
"At half past eleven."
Nathan smiled while Mrs Hargreaves came farther into the room and looked toward the travelling carrier. "Everything?" she asked.
"Almost."
"Your warm clothes are packed, your medical materials are with Willit's case and the rat's food is separate. Your papers?"
"Tomorrow morning."
"France first."
"Yes."
"Then America."
"Yes."
"And I am still not entering a hospital merely because you become interested in something."
"Agreed."
"You said that very quickly."
"Because I agree."
Mrs Hargreaves regarded him suspiciously anyway, then glanced toward Horsley as the rat resumed nosing at the puzzle. "You are responsible for him."
"I know."
"I mean all of him. Feeding, cleaning, carrying and whatever else one does with a rat on a ship."
"I already do those things."
"You do some of those things and other people discover the rest need doing."
"That is slander."
"It is housekeeping."
Nathan smiled, and Mrs Hargreaves turned toward the door before he called after her.
"You can still change your mind."
She stopped. "About coming?"
"Yes."
"Do you want me to?"
"No."
"Then why say it?"
"Because wanting you there doesn't make you obligated."
Mrs Hargreaves studied him for a moment, the suspicion leaving her expression and something quieter taking its place. "Nathan, if I did not want to go, you would know."
"That is true."
"And somebody has to make sure you remember food between epidemics."
"That sounds suspiciously like an obligation."
"It is self-defence. Hungry scientists are irritable."
"I am not irritable."
Mrs Hargreaves looked at him.
Nathan reconsidered. "Not unusually."
"That is not the defence you think it is."
She reached the doorway before turning one last time. "And if anyone at the port asks why you are taking a rat across the Atlantic, you are explaining it."
"That seems fair."
"Preferably without giving them a lecture."
"I wasn't planning to."
Mrs Hargreaves looked at him.
Nathan smiled. "A long lecture."
"That is precisely what worries me."
After she left, Nathan remained at the desk and read the Kansas report once more from the beginning, not because he expected the words to change but because tomorrow he would begin asking questions and answers had a way of changing how original evidence looked. He wanted to remember what they knew before hindsight began pretending it had known more: Camp Funston, Fort Riley, March, a sudden concentration of illness, more than a hundred soldiers reporting sick, secondary pneumonia in some cases, insufficient material, inconsistent descriptions and a cause the Institute could not determine. Perhaps ordinary influenza, perhaps several illnesses grouped together, perhaps something not properly characterised; no proof of origin, no proof of connection to Europe and no proof of novelty.
Nathan preferred it that way for now because ignorance admitted was a question, while ignorance disguised as certainty became an answer nobody thought to test.
The aeronautical folder remained on the far side of the desk and he looked at it for several seconds before deciding against taking it. "No," he said, causing Horsley to look up. "Mallory can survive without me."
Nathan packed the Kansas material first, followed by the European respiratory reports, Willit's summaries, maps and several blank notebooks, leaving the aviation folder where it was before crossing to Horsley's enclosure and checking the latch. The rat came closer while his fingers worked the catch, nose lifting toward Nathan's hand, and Nathan noticed his attention settle upon the movement.
"You're watching that too."
Horsley remained still.
Nathan deliberately changed the angle of his hand, operated the latch once more and watched the rat's head follow the motion. It meant nothing yet, and Nathan refused to let interest turn into certainty merely because he wanted the result, so he secured the catch and stepped away without another trial.
Tomorrow Horsley would move into the new carrier, Mrs Hargreaves would leave The Knapp instead of standing at its door while Nathan disappeared somewhere else, and T would cease being the black-armoured figure known inside the Institute before beginning the journey beneath an identity no Institute worker would ever see connected to him. France would come first, then the Atlantic, America and finally Kansas, assuming the war, the sea, bureaucracy and whatever waited at the other end allowed Nathan's plans to survive contact with reality.
He lowered one lamp and extinguished another, leaving the office in warm half-darkness while the windows reflected the room back at him. For a moment he saw his own face in the glass, still almost unchanged, too unchanged, while behind that reflection sat Horsley, the reports and years of work that had altered everything around Nathan while leaving too little evidence upon him. Margaret came briefly to mind, along with the quiet certainty in her voice when she had told him a mother would always know; then his father's grave, Thomas and Clara followed, all of them carried forward by time in ways Nathan increasingly suspected he would not be.
He looked away from the reflection.
This time Mrs Hargreaves would travel with him rather than stand at The Knapp and watch him leave, and Nathan was glad. The simplicity of the feeling surprised him enough that he chose not to dissect it; some things became less honest when examined too aggressively.
He picked up the travelling case and reached the door just as another faint wooden click came from behind him, then turned and found Horsley beside the opened puzzle once again, the altered mechanism solved.
"Of course," Nathan said, smiling at the rat before deciding not to reset it. "There'll be time on the journey."
Outside, the rain had stopped although water continued dripping from the eaves and the branches beyond the windows moved softly beneath the wind. Far away the Institute remained awake behind scattered windows, Hale almost certainly still revising travel arrangements while Willit's clerks worked through hospital records Nathan had ordered them to reconsider and Mallory's engineers turned a supposedly fixed limitation into something measurable. Somewhere inside those same walls T would be finishing another circuit in black armour, faceless to everyone who passed him, checking locks and barriers and asking an unfortunate electrician why a relay was only probably responsible for a delay.
The Institute was asking questions without Nathan standing in the room, and that pleased him.
Across the Channel men fought, travelled, slept in crowded quarters and became sick for reasons physicians might or might not understand, while across the Atlantic troopships moved between continents and American railways turned enormous distances into timetables. Somewhere within that machinery lay Kansas, where soldiers had begun coughing weeks earlier and Nathan's Institute possessed only one answer honest enough to trust.
Undetermined.
And he was going to find out why.