Silence pressed down inside the cavern. Sirius lunged at the archway without hesitation—only to slam shoulder-first into solid rock. A dull thud echoed off the walls.
The carved outline of an arch remained perfectly visible on the stone, like water-worn relief. But beneath it there was no passage—just more unyielding rock. Voldemort's protective magic wasn't a simple push-button mechanism.
Kreacher stood a respectful distance away. He'd known this would happen—he'd lived through it twice already, thirteen years earlier.
When Voldemort had first turned the locket into a Horcrux, he'd been only two years out of Hogwarts—still lurking at Borgin and Burkes, quietly studying the Dark Arts while concealing his twisted soul. It wasn't until thirty years later that he finally hid the finished Horcrux here and layered the cave with vicious, sadistic protections.
By then he was the most powerful Dark wizard in history… yet his taste remained crude. No elegance. No grandeur. Just the clumsy tricks of an overconfident apprentice showing off.
Both Melvin and Dumbledore already knew the correct way to open the passage. They simply waited—silent, patient—for Kreacher to act.
"This is the Dark Lord's magic," the elf rasped. His voice bounced hollowly around the cavern. "The arch has no lock. No key. A visitor must pay a price to pass."
Sirius's head snapped up. "What price?"
"Blood. Fresh blood."
Sirius's voice dropped dangerously low. "How did Regulus get through?"
"Master Regulus… paid the price." Kreacher's thin frame trembled.
Sirius went very still. His eyes flicked to the elf with cold contempt. "You're a disgraceful servant."
Without another word he drew his wand across the inside of his forearm. A thin silver flash. Crimson welled instantly. He flicked his wrist; blood sprayed across the stone. Droplets raced down the rock face, seeking tiny crevices, soaking in.
The archway flared again—this time with blinding white light. The illusion of sculpture vanished. A real opening yawned beneath it.
They stepped through one by one, shoulder to shoulder.
Before them stretched an endless black lake. The water looked bottomless in every direction—same depth, same darkness. No visible shore except straight ahead: a small rocky platform glowing with sickly green light at its centre.
Apparition was impossible here. The enclosed space felt like a cage. The darkness was thicker than night—almost suffocating.
"Undetectable Extension Charm," Melvin murmured. He snapped his fingers.
Dozens of soft blue flames rose like streetlamps along the water's edge, spreading gentle light. The cavern suddenly felt less oppressive.
Kreacher shuffled forward, feeling along the shore. Sirius stayed close behind. Their footsteps echoed sharply on narrow ledges until the elf stopped at an unremarkable patch of rock.
Kreacher reached into the dark water.
Through magical perception and the faint ripples, Melvin sensed the outline of a small boat resting on the lakebed—crude hardwood construction, like something a fisherman might cobble together, except laced with Dark magic.
"A boat?" Sirius asked, voice tight. He watched as Kreacher hauled up a corroded copper chain. Greenish rust clouded the water. The boat rose like a ghost—emitting its own faint, sickly glow.
"The Dark Lord hid this boat here," Kreacher whispered. "Master Regulus said… the Dark Lord needed a way to cross the lake safely when he wanted to check on or retrieve the locket. So the things in the water wouldn't be disturbed."
"The boat carries powerful concealment charms. It muffles movement. As long as you stay aboard, the creatures below won't attack. But eventually… they'll realise you aren't the Dark Lord. They'll realise you're the enemy he ordered them to guard against."
Melvin examined the craft, drawing on knowledge acquired from a certain "kind mentor" named Tom. "Thousands of Inferi underneath. Wizards. Muggles. All innocents killed by Voldemort's wand."
Sirius shivered violently. "Is he… down there?"
"We'll only know when we reach the island," Dumbledore said softly. "We must hope he was never pulled under."
Kreacher had already clambered aboard. Sirius followed, crouching low. The boat sat dangerously low in the water—barely room for two.
Sirius looked back. "Headmaster—Melvin—come on. We can squeeze."
Melvin shook his head with a faint smile.
Dumbledore chuckled quietly. "Voldemort designed this boat with only magical strength in mind—not weight or space. The spell permits exactly one wizard per crossing."
Sirius glanced at Kreacher. "But—"
"House-elf magic isn't counted." Dumbledore's eyes twinkled. "You fit the criteria perfectly, Sirius. But if Melvin or I step aboard… the boat will capsize instantly. And the Inferi will wake."
"Then how will you—"
"We'll find another way. Go on ahead."
Sirius gave a half-understanding nod. He coiled the chain in the bow, hunched low, and the boat slid silently forward—gliding toward the green glow on the distant island. The only sounds were the gentle lap of water against the hull and the soft hiss of the bow cutting the surface.
He never once doubted they would reach the other side.
One was the most famous living wizard in the world. The other could chase lost relics across time itself. What Dark magic could possibly stop them?
Melvin crouched at the water's edge. He extended a hand toward the surface. Cold, clammy magic rose like coiled serpents—poised to strike.
"Magical historians have a theory," he said quietly. "They say the witch Viviane laid a trap at the bottom of her lake—Inferi, swamp trolls, merpeople. She enchanted the water itself. Lured Merlin under. Flooded his mouth and nose so he couldn't incant. Stole his wand so he couldn't cast. Let the Inferi pin him down so he couldn't surface. A perfect sealed prison. His final resting place."
Dumbledore gave a small shake of the head. "A chilling image. Any suggestions, Melvin?"
"I think you should take the boat," Melvin said. "When it measures magical strength, it won't count Sirius. Twelve years in Azkaban left him severely weakened—he still hasn't fully recovered. Voldemort calibrated this for his own future power level. Compared to a legendary wizard's magic… an ordinary wizard's might as well be nothing."
Dumbledore's eyes crinkled with amusement. "And the same logic applies to you, doesn't it?"
"Exactly."
"Hey!" Sirius's indignant shout drifted back across the water. "I'm not that far away yet—I can still hear you!"
"I'll go first," Dumbledore said cheerfully—completely unabashed at being caught.
A soft orange flame bloomed overhead. A musical trill echoed through the cavern. Fawkes burst from the fire, circled once around the old Headmaster's head, wings trailing brilliant light—the brightest thing in this pit of darkness.
Dumbledore raised a hand. Golden tail feathers closed around his fingers. Flame erupted outward—swallowing phoenix and wizard alike.
The fire winked out.
Seconds later, fresh light bloomed on the island—Dumbledore had arrived ahead of the boat.
As expected. Like house-elves, phoenixes ignored anti-Apparition wards. Hogwarts or this cave—it made no difference.
In the old timeline, Dumbledore had brought Harry here near the end—bleeding, rowing, forcing the boy to drink poison sip by sip. A final, desperate lesson before death.
Now it felt different.
Icy cold—Dementor-cold—rose from the lake and wrapped around Melvin. Gooseflesh prickled along his arms.
Dumbledore and Sirius had crossed.
How would he?
He studied the water again. An Inferius drifted upward—face inches below the surface. For a moment their eyes met. Empty sockets. Dilated pupils. Deep inside… a faint glimmer. Like spiderwebs. Like trapped mist. Like desperate hunger.
The same look he'd seen in Dementor eye-sockets.
How did Voldemort control them?
A thought flickered through Melvin's mind. His black pupils flashed with silver light. Magic extended outward—carrying intent—brushing the frozen surface.
I will raise my wand toward the lake and part the waters. I will cross to the island on the far shore.
Be silent. Do not cry out. Do not be afraid. Simply stand still.
Legilimency. False Memory Charms. Communicating with soulless beings—this was the method he'd learned from a very young Tom Riddle. He wasn't certain it would work on Inferi.
He waited.
Then he pressed his palm flat against the water and whispered.
The words were soft—almost lost in the vast cavern.
He rose. And did something that would have made Sirius's jaw drop.
He stepped straight out—onto the lake of Inferi—like a man deliberately walking into his own grave.
Merlin himself had been murdered in a lake like this. Even Dumbledore had avoided touching the water. Who knew what traps Voldemort had left—poison, curses, worse.
Waves rippled outward.
The instant his foot would have broken the surface, the bubble reformed—larger this time.
Water spiralled around his feet. A transparent sphere expanded rapidly outward—dozens of feet across. Lake water was forced aside. The bubble sank until Melvin stood on its bottom—walking on water.
Below him the Inferi hung motionless. Thousands of pale, bloated faces tilted upward—watching the young wizard glide across their prison toward the island at the centre.
A soft thunk.
Sirius's boat tapped rock.
He secured the chain and stepped onto the smooth stone platform. Empty except for the stone basin at its heart—glowing vivid emerald.
Before he could approach it, Melvin arrived—walking straight across the water as though it were solid ground.
Sirius's eyes dropped to the lakebed. Through the parted water he saw them—hundreds, thousands—staring up with those empty, fog-filled eyes. Corpses bobbed gently in the current. Swollen. White. Hair and robes drifting like smoke.
No sign of Regulus.
Sirius's throat worked. He couldn't tell whether he felt relief or something worse.
Dumbledore already stood beside the basin. The others joined him.
They stared down at the basin—brimming with luminous green liquid that gave off its own sickly phosphorescence.
"This is poison," Kreacher whimpered. "Kreacher drank it once. Saw terrible things. Felt his insides burning. Needed water to put out the fire… but the water was full of corpses!"
His whole body shook. "Later Master Regulus drank it too. He ordered Kreacher to switch the locket. Then ordered Kreacher to leave."
Sirius's eyes were scarlet-rimmed. He reached toward the liquid—only to meet invisible resistance. No matter how hard he pushed, his fingers couldn't break the surface.
Melvin and Dumbledore tried as well. Same result.
"Remarkable magic," Melvin murmured in genuine admiration.
"Ancient runes woven in," Dumbledore agreed. He tested several spells. Nothing happened—except the green glow brightened slightly. "No Vanishing. No scooping. No Transfiguration. No alteration of the liquid's properties. It isn't just poison—it's part of the cave and lake now. An extension of the space itself."
"Which means…" Melvin finished, "it can only be removed by drinking."
Sirius's jaw tightened. "Then I'll drink it."
"That's Regulus's locket!" he snarled. "I'm getting it back."
Kreacher looked up at Sirius—then closed his eyes and waited for the inevitable order. His frail body shook harder than ever.
He still remembered the agony—swallowing molten rock. Organs drying out. Every breath scorching his windpipe. The desperate crawl toward water filled with corpses.
But no order came.
When the elf finally dared to open his eyes, he saw Sirius—his hated young master—already raising a stone goblet toward the basin, ready to drain the poison in one long swallow.