Chapter 1: A Call at 3:00 AM

It was precisely 3:00 in the morning when Lin Mo jolted awake, drenched in a fine layer of sweat. His breathing was shallow, his skin clammy, as if he had just escaped a nightmare—though none he could remember. Instinctively, he reached out in the dark for his phone on the nightstand.

The screen was lit.

An incoming call was flashing on the display.

No number. No location.

Just one word: Unknown.

His brows furrowed. He hesitated for a moment, thumb hovering over the green icon. Then he answered.

“Hello?”

Silence.

The line was dead quiet. Not even static. Not a hum, not a breath. It was the kind of silence that felt dense—occupied.

Just as Lin Mo was about to hang up, a sound finally emerged. A faint, irregular breathing. Sharp, uneven, unsteady—as if someone was hiding in complete darkness, struggling to stay calm, heart pounding out of rhythm.

Then came the dripping.

A slow, consistent, almost ceremonial drip... drip... drip...

It didn’t sound like anything from his apartment. No leaky faucet, no ticking clock. It felt distant yet chillingly close, like it was seeping through the phone itself from another dimension.

Lin Mo’s skin prickled. His fingers began to tremble.

“Who are you?” he asked, voice lower than he intended, throat dry.

Still, no response.

The line stayed open for five more seconds.

Then the call ended with a soft click.

He let out a shaky breath, scoffing under his breath. Probably just some prank or a spoofed number. Weird, but not unheard of. He was about to set the phone back down on the nightstand when something else popped up on the screen.

A system notification.

New Contact Added: 13F

His heart skipped a beat.

That couldn’t be right.

Lin Mo lived in an old residential building built in the early '90s—twelve floors in total. From the moment he’d moved in, he’d studied the structure obsessively. Every floor. Every neighbor. Even the elevator’s scratches and quirks. There was no thirteenth floor.

And yet, there it was: 13F—now sitting calmly in his contacts list.

His hands shaking, he opened his address book. There it was. “13F,” listed neatly with no profile photo and no phone number. Just a name.

He checked the call log.

Nothing. No incoming call. No missed call.

But he’d answered it. He was sure.

He sat up in bed, glancing around. The air in the room felt heavier. The temperature had dropped, just enough to notice. Outside the window, the curtains stirred ever so slightly as if a damp wind had brushed past them.

Something was off.

Driven by a mix of dread and inexplicable curiosity, Lin Mo stood up and slipped on a jacket. He had to see for himself.

The hallway outside was deathly quiet. The kind of quiet that makes your ears ring. The kind that only old buildings at night could manage—every creak amplified, every step loaded with suspense. Lin Mo walked slowly toward the elevator at the far end of the corridor.

He pressed the button.

Ding—

The doors slid open with a sigh, and a gust of cold air washed over him.

The elevator was empty.

But the digital floor display above the door... it was glowing red:

13

Lin Mo stepped back involuntarily.

“That’s not possible,” he murmured.

He stared at the number, brain scrambling for an explanation. Maybe a glitch. Maybe the system was old. But he’d lived here for years. Never once had it shown a floor thirteen.

He reached in and pressed “1.”

Nothing happened.

He pressed “Close.”

The button blinked but the doors didn’t move.

Without warning, the elevator began to descend.

The lights flickered. The motor groaned like it was in pain. A distorted hum filled the air.

He backed against the wall, eyes locked on the floor counter.

11... 12... 13

Ding.

The doors opened.

Stillness. A vacuum of sound.

The corridor before him was dimly lit, lined with bare concrete walls. No apartment doors. No number plates. Nothing but a flickering emergency light above a partially open fire exit at the far end.

From that opening came a sound.

Drip... drip... drip...

The same sound from the call.

On the floor near the elevator entrance lay a single black canvas shoe. The kind teenagers wore in high school. Its laces were untied, the tips stained a dark reddish brown.

Blood. Not dry. Not fresh. Still tacky.

A trail led from the shoe toward the door at the end of the hall.

Lin Mo’s heart pounded.

Every logical instinct screamed at him: leave. Go back. Call the police. But something deeper, darker, tugged at him from within. He stepped out of the elevator.

The corridor had no windows. No signs. No vents. Just a featureless tunnel with walls that seemed to pulse with moisture.

He walked slowly, each step echoing unnaturally, like he was walking inside a hollow shell.

The door creaked open at his touch.

Beyond it was a storage room—or at least, that’s what it looked like. The walls were peeling, gray and damp. At the center stood an old rusted hospital bed. On it, nothing.

Except a single yellowed photograph.

He walked up and picked it up.

It was him.

Lin Mo, standing in front of this very building. But not as he was now. He was younger, maybe high school age, dressed in an outdated school uniform. No smile. No emotion. Just staring into the camera.

But he had never posed for this picture.

In the background of the photo, the building had thirteen floors. The missing floor was visible behind him like it had always existed.

On the back of the photo, scrawled in what looked like red crayon or marker:

“Welcome home, 13F.”

He looked up.

In the mirror on the far wall, something was standing behind him.

A girl. Wearing a red dress. Hair tangled, face hidden. In her hand, she held the canvas shoe.

The one from the hall.

Before he could turn around, the lights snapped off.

Darkness consumed the room.

When Lin Mo opened his eyes again, the sun was shining.

He was in bed.

Morning light spilled gently through the curtains, casting familiar patterns on the floor. The oppressive cold from the night was gone, replaced with a deceptive warmth.

He sat up slowly. Maybe it was a dream. A vivid, twisted dream.

He grabbed his phone.

No missed calls.

No new contacts.

No “13F.”

He allowed himself a small laugh of relief and swung his legs over the edge of the bed.

That’s when he saw it.

On the floor, just beside his feet—was the black canvas shoe.

Laces undone.

A thin smear of dark blood trailing from its edge.

Just like the photo.

Inside the shoe, neatly folded, was a small, white paper note.

He picked it up with trembling fingers.

The message was written in red ink, in the same jagged handwriting as the photo.

“You are now a resident of 13F. The contract is active. Escape is invalid.”

Lin Mo collapsed backward, his back hitting the wall as the realization set in.

It wasn’t a dream.

It was a transfer.

A shift in dimension.

A crossing into a floor that shouldn't exist.

Outside, from the hallway, came the sound of laughter.

Light, high-pitched. Childlike.

But wrong.

He staggered to the window and flung the curtains aside.

Nothing.

The street below was normal. Familiar. But it didn’t feel the same.

From somewhere in the corridor, the elevator chimed.

Ding.

The digital display outside his apartment door flickered.

13

And then—slowly—the elevator doors opened.

There was someone waiting inside.