There were many places at Hogwarts students weren't technically allowed to go—places marked on dusty rulebooks or spoken of in whispers. The Forbidden Forest, of course. The Room of Requirement, which wasn't on any map but everyone eventually found. Even Professor Longbottom's greenhouse after dark, which Scorpius claimed was haunted by a carnivorous cactus.
But few places were as quietly, absolutely, avoided as the caves beneath the Black Lake.
There were no rules against them. No hexes. No chains. But every student knew.
You didn't go there.
Even Peeves the Poltergeist never floated near the entry points. And ghosts avoided the lower passageways that led down into the cold places. Whatever lay under the surface of the lake was older than the school. Older than the Founders. Maybe older than magic itself.
Which, unfortunately, was exactly where Albus Severus Potter was headed.
The Passage Behind the Bath
They met, as they had several times now, in the Prefects' Bathroom—despite the fact that none of them were actually prefects.
It was early. Very early. Long before breakfast. The castle was still asleep, wrapped in mist and silence. The stained-glass windows that lined the massive bath shed soft light in blues and greens across the steaming pool. The occasional bubble rose from the enchanted faucets, gurgling softly.
Albus sat on the edge of the tiled pool, arms folded.
Scorpius stood barefoot in a towel, staring at a very old section of the back wall. "I still say this entire thing feels like an elaborate excuse to see me shirtless."
Fiona ignored him. She was crouched near the floor, wand-tip pressed into a patch of pale tiles. "This section of the floor predates the castle. I found references in an archived maintenance log written in Gobbledegook."
Albus raised an eyebrow. "You read Gobbledegook?"
"Only badly," she admitted. "But diagrams help."
With a muttered charm and a sharp click, a seam appeared in the stone, revealing a narrow hatch. A blast of cold air rolled out, carrying the scent of moss, salt, and something older—like stone and bone and silence.
Albus leaned over. "This goes down to the lake?"
"Sort of," Fiona said. "It connects to the old sub-reservoir tunnels. They were part of the original defensive architecture—used for flooding corridors during sieges. But they go deeper now. Much deeper."
Scorpius peered in. "Anyone ever... not come back?"
Fiona looked at him. "Do you want the honest answer or the comforting lie?"
He hesitated. "Lie first."
"No one's ever gone down there," she said sweetly. Then: "That lived to write about it."
Breathing Water
They prepared carefully.
Gillyweed capsules, stored in waxed paper and smuggled from the Potions stores. Waterproof wand sheaths, enchanted cloaks woven from kelpie-hide fibers. Fiona passed Albus a stone disc no larger than a coin.
"Breath anchor," she explained. "Even with Gillyweed, magic-infused water messes with your perception. This will keep your lungs steady."
Albus examined it. "Where did you get all this?"
"My aunt," Fiona said casually. "She's a cursebreaker. Works in deep-sea tomb recovery."
Scorpius blinked. "That's a real job?"
"Dangerous one," she replied. "She lost her foot to a singing clam once."
Scorpius opened his mouth, then closed it. "Let's just go."
They swallowed the capsules and dove.
Descent Into Darkness
The water hit like a wall—cold and thick, dragging the warmth from their skin in a single heartbeat.
Albus felt his throat close, then shift. His lungs convulsed, then settled into a strange, slow rhythm. Gills flared at the sides of his neck. Breathing water was like breathing stone at first, but then—something shifted—and he was breathing, and it was somehow right.
They swam downward, guided only by wandlight and instinct.
The tunnel walls were ancient—stone worn smooth by time and tides. Algae pulsed faintly with bioluminescence, throwing strange shadows. Occasionally, a school of spectral fish darted past, translucent and silent.
It wasn't quiet down here.
There was pressure. A vibration in the water. Not sound exactly, but something deeper. Like a heartbeat, slow and distant. Rhythmic.
Boom… boom… boom…
Albus felt it through his bones. In the mark on his wrist.
They passed through an arch lined with ancient glyphs, and then—
The ruins appeared.
The Second Gate
It rose from the lakebed like a grave.
Black stone columns, half-collapsed, lay scattered in a wide circular depression. At the center stood a twisted archway, slick with algae and time. It looked ancient—and wrong. Too tall, too thin, the angles almost Euclidean, but not quite.
Scorpius swam beside Albus, eyes wide. "That's definitely the creepiest architecture I've seen since that one Defense textbook that screamed when you opened it."
Fiona pointed with her wand. Floating in the dead center of the archway was a glowing blue orb.
It shimmered like a flame suspended in water.
Albus felt it call to him.
He drifted closer.
The mark on his wrist was burning now—warm, not painful. Familiar. Almost eager.
When his hand touched the orb—
Everything changed.
The Gate Opens
A pulse of magic exploded outward.
The water buckled around them. A wall of force hurled Albus backward. Columns cracked. Silt erupted like smoke. Statues that had stood still for a thousand years shook with sudden life.
In his mind—not ears—a voice rang out:
"Two have turned. The third begins. The serpent stirs beneath the root."
Then, silence.
Albus hovered in the water, chest heaving.
The orb had vanished.
The gate now shimmered faintly—open, in a way that made no logical sense. The archway itself remained solid, but space within it twisted like a whirlpool of light and shadow.
Scorpius swam to him. "Please tell me you did not just open the way for some kind of undersea apocalypse beast."
Albus swallowed hard. "I think… I opened a path. A memory? A tether?"
Fiona pointed suddenly. "Look."
The Watcher in the Deep
At the far edge of the ruins, between broken statues and crumbled stone—
Something moved.
A shape.
Massive. Slow. Coiled.
It was barely more than shadow. But then, two eyes blinked open—glowing yellow, vast and ancient.
It watched them.
Not attacking.
Not approaching.
Just… waiting.
A creature bound to the gate. Or maybe to the one who touched it.
Albus felt its gaze like a weight against his chest.
Scorpius grabbed his cloak. Fiona signaled to retreat.
They turned and kicked upward, leaving behind the open gate, the broken ruins, and the thing that watched from the shadows of the deep.
Surface and Shock
They broke through the surface of the bath in a rush of gasping breath and sloshing water.
Scorpius flopped onto the tile, coughing up pondweed. "I am never eating sushi again."
Fiona climbed out second, soaked and silent, eyes wide with thought.
Albus knelt beside the water, still breathing heavily. "That was the second gate. I felt it. It knew me."
Fiona spoke slowly. "It activated because of you. The orb responded to your mark."
Scorpius groaned. "So this is going to keep happening, isn't it? Until what—five gates are open and we unleash whatever ancient horror is waiting to eat the school?"
Albus didn't answer.
Because deep down, he feared the answer was yes.
The Bleeding Book
Back in the common room, wrapped in dry robes, Albus unwrapped the black journal.
It was already open.
Ink bled across the pages, faster than ever.
Words scratched themselves into the parchment in his own handwriting:
"The Second Has Stirred.""It watches. It waits.""Do not trust the roots.""He walks cloaked in many names."
Then, on the final page:
"The Fifth shall fall to blood."
The ink ran down the page, dark and shimmering like blood in moonlight.
Fiona stepped back, her expression pale.
Scorpius stared at the words, voice quiet for once.
"This… this isn't just a puzzle anymore. This is a war map."
Albus felt the mark on his wrist pulse again.
And in the back of his mind, beneath the weight of water and time and memory, he felt it:
A voice.
Calling.
Waiting.
The Third Gate was waking.