I gripped the bottle of "High-Acidity Soil Neutralizer" (my extra-strength cleaning vinegar) and looked at the main intake of the copper listening tube. It was disguised as a decorative relief of a lion's head.
"Let's see how well you listen to this," I muttered.
I tipped the bottle.
The reaction was instantaneous. As the concentrated vinegar hit the years of lime-scaling and calcium buildup inside the "drainage" tubes, it didn't just flow. It hissed. It started to growl.
Suddenly, a rhythmic thump-thump-thump echoed through the walls. I had triggered a chemical chain reaction. Below us, in the Principal's office, the primary acoustic receiver (which I assumed was a large horn or a glass resonator) was currently being fed a cocktail of carbon dioxide and caustic foam.
"Master Verne?"
The Grey Cloak's voice was like a cold splash of water. He was walking toward me, his hand resting on the hilt of his sword. He sniffed the air, his nose wrinkling. "What is that smell? It smells like... a salad."
"Salad? Oh, Master Courier, you have a refined nose!" I turned around, frantically waving my hands to disperse the vinegary steam rising from the lion's mouth. "It's the acetic-cleansing protocol! You see, the lichen growing in these pipes is a very specific strain of Lecanora muralis. It thrives on alkaline stone, so one must use a mild acid to... well, to 'de-encrust' the artery!"
GLUG. POP. HISS.
The wall behind me shuddered. A muffled, wet explosion echoed from the floor below, followed by a distant, high-pitched shout from Principal Albrecht.
The Grey Cloak narrowed his eyes, stepping closer. "What was that sound? It sounded like an explosion in the acoustics."
"Explosion? No, no!" I stepped in front of him, blocking his view of the bubbling lion's head. I grabbed my notebook and shoved a diagram of a subterranean silt-trap into his face. "That was merely a Hydro-Pneumatic Burp! It's a common occurrence when air is trapped in a non-linear drainage system. In fact, if you look at this chart from the Great Flood of 188, you'll see that a burp of that magnitude suggests a blockage of at least three kilograms of organic matter!"
"Verne, move aside," the Grey Cloak commanded, his voice dropping an octave.
"I cannot!" I cried, putting on my best 'panicked academic' face. "If you interrupt the pressure-balance now, we could face a Secondary Gutter Recoil! Do you know the tragedy of the Third-Century Sluice Gates? Thousands of documents lost to a back-pressure surge! It starts with a simple fizzing—much like we hear now—and leads to a catastrophic release of stagnant 'grey water'!"
I started walking toward him, forcing him to back up or be hit by my waving arms.
"Let me explain the physics of the 'Siphon Effect' in ancient masonry," I droned, my voice becoming a relentless, hypnotic wall of sound. "When a liquid of a different viscosity—like my cleanser—interacts with the porous nature of the granite, it creates a vacuum. This vacuum, according to the Principles of Percolation, must be filled. If it isn't filled by air, it will be filled by... more liquid! Thus, the 'burp'!"
Below us, another SPLAT echoed. I could only imagine Albrecht's office currently looked like a giant had sneezed a bowl of vinegar-bubbles onto his desk.
"You are babbling," the Grey Cloak snarled, but I could see the familiar "Boredom Glaze" taking over his eyes. The sheer density of my nonsense was physically pushing him back.
"Babbling? I am lecturing!" I adjusted my spectacles with a sharp clack. "Now, if we consider the friction coefficient of copper versus lead in a high-humidity environment like this hallway, we find that the acoustic resonance—which you mistakenly think is an explosion—is actually a harmonic vibration of the pipes! It's physics, man! Boring, beautiful physics!"
He took another step back, his hand leaving his sword to rub his temples. "Enough. The Principal is shouting. I must see to him."
"Ah! Tell him to watch out for the Capillary Backwash!" I shouted after him as he turned and sprinted toward the stairs. "It's very hard to get the smell out of silk!"
I waited until his footsteps faded before I turned back to the lion's head. The hissing had stopped, replaced by the satisfying sound of dripping liquid. The "Listening Network" was officially dead, its copper veins dissolved and choked with foam.
I leaned against the wall, my heart hammering against my ribs. I looked at my hands. They were shaking.
If they dare to make you lose even a single hair... Avaris's words echoed in my mind.
"Well," I whispered, wiping a bead of sweat from my forehead. "The hair is still there, but the Academy is going to smell like a pickle jar for a month."
I heard a soft psst from the shadows of a nearby doorway. I turned, clutching my trowel.
Cyrus and Mira were huddled in the darkness of the broom closet, their eyes wide with terror and a spark of something that looked dangerously like hope.