Knock.Knock.Knock.
The sound came again. Not angry. Not rushed. Just patient.Like it knew it had time. Like it had knocked before. On other doors. On other lives.
"Oppa…" the voice came again.Closer now. Louder. Like it was just a breath away."Let me in."
Kim Jisoo's fingers dug into the metal frame of the chair beside him. His knuckles turned white. His ears rang.
It's not her.
That much he knew. His sister's voice was softer. Warmer. This one was too smooth. Like someone had fed a memory through a machine and pressed play.
Knock. Knock. Knock.
"Why won't you answer me, Jisoo?"The voice cracked, just slightly. As if hurt. As if sad.
His breath caught. Not because he believed it—but because part of him wanted to.
That was the trap.
It wanted him to open the door.
He stayed frozen in place, chest rising and falling with shallow breaths. Muscles tight. Pulse slamming against his ribs.
Then the voice changed. Just slightly."Oppa, I'm cold. I've been looking for you."Louder now."You said we'd be together, remember?"Too loud."You said you'd protect me."Then:"You lied."
His skin went ice cold.
Knock. Knock. Knock.
This time the knocks were too slow. Like whatever was behind the door didn't care how long it waited. Like it didn't need to rush.
"Let me in."
Then silence.
Jisoo waited. Not daring to breathe.
Nothing.
Then—
The sound of footsteps.Heavy, dragging.
It moved to the neighboring door. A woman lived there, he remembered. Alone. She had a cat.
He pressed his ear to the wall.
Knock. Knock. Knock.
Same rhythm. Same patience.
Then the voice again."Oppa…"
Jisoo slid to the floor, heart pounding. He pressed both hands over his ears, as if it would block the sound from inside his brain.
His instinct screamed. Not fear. Worse. A warning so primal it bypassed logic.
That thing wasn't human.It wore her voice like a mask.
He wanted to vomit. But there was nothing in his stomach. Just acid and air.
He sat there for minutes, maybe longer, until the footsteps moved away. Fading. Down the hall. One knock at a time.
Then silence again.
Still, he didn't move.
Not until his body calmed. Not until the shaking stopped. Not until the tight grip in his gut loosened enough to think.
Then, slowly, he pulled himself to his feet.
His back ached. His head was hot. But his mind was clear now.
This was real.
And it was just beginning.
He pulled the map off the wall.
Unfolded it across the table.
The paper was covered in red circles. He ran his finger across them. One, two, three… twenty in Seoul alone. Storage caches. Supplies. Hidden drops. Small but essential.
Around the country? Fifty more. Some in forests. Some in abandoned towns. One in a locked freezer inside a meat factory. One under an empty bus terminal.
It had taken years.
And people had mocked him.
But now, the world had stopped laughing.
He reached into the drawer and pulled out a marker. Circled one location in bold red: Black Hollow Lab. A code name. Not government. His own.
It was deep under Mount Surak, just outside the city. The entrance disguised in a dead-end service tunnel. Concrete sealed. Steel reinforced. He built it himself with hired workers—none of whom knew the real purpose.
They thought it was a bunker. It was more than that.
It was his lab. His sanctuary.
It had full solar backup, water filtration, three months of food, and a secure internal network with all his research. Radiation monitors. Signal detection. A prototype AI to analyze anomalies.
If he was going to understand what was happening—he had to get there.
But first, he had to leave this apartment.
And the city was no longer safe.
He moved to the closet and pulled out a duffel bag. It was already packed: compact gas mask, iodine tablets, encrypted drive, burner phone, and two custom-made stun rods. The rods weren't legal, but they worked. Enough voltage to fry a grown man unconscious.
He strapped on light armor under his jacket. It wouldn't stop bullets, but it could turn claws. Or teeth. Or whatever was out there now.
Then he walked to the bedroom and reached under the bed. Pulled out a sealed box.
Inside: weapons. Not guns—too loud, too much attention.He chose a compound bow, collapsible, and thirty carbon-fiber arrows with razor tips. Silent, clean, deadly.
He slung the bag on his back, checked the seals on the windows again, and then… he stopped.
Turned toward the door.
Still closed. Still locked.
But behind it, something had stood. And whispered.
It would come back. They all would.
He pressed his palm to the jade pendant at his neck. Still warm. Still glowing faintly. It pulsed like a heartbeat. A strange comfort.
His mother gave it to him. He never understood why.
Now he wondered if she had known.
If maybe… she'd left not to abandon them—but to run from something.
The thought hurt. But he locked it away.
There was no time for grief.
Only action.
He took the back exit.
Three floors down. Through the laundry room. Into the underground garage. He had scoped every escape path years ago. The door creaked, but nothing waited on the other side.
He slipped into the shadows, moving fast and low.
Outside, the sky was darker now. Not night. But wrong.
No wind. No clouds. Just thick grey hanging above, like ash that never fell.
The streets were nearly empty. A few cars sat abandoned in intersections. Doors open. Lights off.
A man stood at a crosswalk, unmoving. Staring straight ahead. Jisoo watched him from behind a mailbox.
The man didn't blink. Didn't speak.
Just… stood there.
Then, slowly, the man tilted his head back—and smiled.
Not a human smile.
A wide, stretched grin that tore skin. Teeth too many. Eyes too black.
Jisoo slipped into the alley and didn't look back.
Whatever was touching the light was changing people.
Turning them into… something else.
He had to move faster.
By the time he reached the edge of the city, the sky had darkened more. Not just from the light—but from smoke.
Fires had started in the distance. Screams echoed now and then. Gunshots here and there. Sirens wailed, but only briefly.
He stayed off the main roads. Used alleys, rooftops, sewer tunnels. He had every route memorized.
The mountain came into view.
Mount Surak.
A wall of rock and trees. Quiet and ancient.
He reached the utility entrance hidden behind an old train line. It was covered with vines and debris.
He knelt, cleared the path, and punched in a hidden code on a keypad under a rock. The panel clicked. The door slid open just wide enough to let him through.
Inside: cold darkness.
He sealed the door behind him.
The tunnel stretched into black.
He turned on a red-tinted flashlight and moved quickly.
Down five hundred meters. Past sealed checkpoints. Old power lines. Forgotten stations.
Then finally—his door.
Black steel. Marked with a simple symbol: a jade spiral.
He placed his hand on the scanner.
The lock clicked.
The door hissed open.
He stepped into Black Hollow.
Lights blinked on.
Cool air flowed.
Screens glowed.
He dropped the bag and moved to the central console. Pulled up the main interface.
His AI, named RAIN, activated.
RAIN: "Welcome back, Kim Jisoo. Alert level: RED. Unknown anomalies detected."
Jisoo's hands flew across the keyboard.
"Run full scan. Atmospheric, solar, radiation, biosigns, signal bleed."
RAIN: "Scanning. Estimated completion: 7 minutes."
He pulled up the camera feeds he had hidden around the city. One showed the man from the crosswalk—now crawling on all fours, chasing something. Another showed a crowd of people… standing still in a shopping mall. Not moving. Not blinking.
Waiting.
He zoomed in.
Their eyes were all black.
Their mouths were twitching.