Chapter 3: The Echo

It was five in the morning, and the first light of dawn had yet to break through the city skyline. Lin Mo stood in front of the living room's floor-to-ceiling window, his expression grim and thoughtful. He hadn’t slept a wink all night. Traces of ink still clung to his fingertips from flipping through his old notes, but what lingered even more deeply was a single haunting thought that circled in his mind like a vulture: 13F.

The phone lay silently on the coffee table, as if everything that happened the night before was nothing but a dream. But Lin Mo knew better. The blood smeared on that red shoelace, the elevator door that opened of its own accord, and the mysterious contact labeled “13F” — they were all real. They were undeniable fragments of a truth hiding behind the façade of the building he had called home for four years.

He lit a cigarette. The curling smoke danced against the window, twisting into hazy silhouettes that looked vaguely human in the dim light.

“Who’s behind all of this?” he muttered, voice barely audible.

He picked up his phone and, after a moment’s hesitation, dialed a number he hadn’t called in a long time.

The line connected with a sleepy, slightly hoarse voice. “Lin Mo? It's early… you dreamed about the thirteenth floor again?”

“It wasn’t a dream,” Lin Mo said quietly. “I saw it. Last night… I was there.”

There was silence on the other end. A beat too long.

“You sure you're not just exhausted?”

Lin Mo exhaled deeply. “Do you remember the disappearance case from Building 13, three years ago?”

The air on the other end of the line seemed to freeze.

“You investigated that case?” she asked slowly.

“I only heard about it,” Lin Mo replied, his tone measured. “It happened around 3 a.m., too. Someone vanished in the elevator. Last thing anyone saw… the floor number stopped at thirteen.”

The woman’s voice became tense. “Lin, I’m serious. Stop digging. That building… it’s not like the others. I’ve seen some strange cases, but this place messes with more than just reality. Even time itself feels… warped here.”

“Time?” he echoed.

“I looked into the building’s blueprints. Officially, it only has twelve floors. But there’s a construction record — a short one — that mentions a thirteenth floor. Then, without explanation, the reference disappears. No approval, no cancellation notice. As if… it was never supposed to exist.”

Lin Mo’s grip on the phone tightened.

“I need the truth, Yan,” he said.

A soft sigh came through the speaker, heavy with unspoken memories. “Okay. I’ll help. But we need to be prepared.”

They agreed to meet at his apartment that evening.

After hanging up, Lin Mo walked into the bedroom and opened his wardrobe. From the bottom, he pulled out a dusty old cardboard box and removed a thick folder from it. It was a collection of personal documents left behind by his late mother, who had once served as the building’s property manager.

He flipped open the folder. One page, yellowed with age, had a scrawled note in pencil:

“Winter, 1979 — 13th floor reappeared. Resident K reports elevator misalignment, hears dripping water and footsteps every night from above.”

He turned to the next page. The handwriting became increasingly chaotic. Some pages were even torn out.

“1980 — Failed to seal the floor. Resident K jumped. Police ruled it a suicide due to hallucinations.”

Then one final line stopped him cold:

“13F isn’t a physical floor. It’s an echo.”

An echo?

Lin Mo stared at the word for a long moment, heart racing. Memories from the night before flashed through his mind — the whispering breath on the phone, the endless dripping water. It wasn’t just hallucination or memory. It was something else. Something replaying. Like an old cassette tape stuck in an infinite loop, replaying a forgotten fragment of sound over and over again.

By six in the evening, Jiang Yan arrived as promised.

She carried a black equipment case slung over her shoulder and wore a calm, analytical expression. A former police detective turned private investigator, Jiang Yan had dealt with her share of cold cases and inexplicable events. She wasn’t easily shaken.

“I brought a thermal scanner, a sound recorder, and an infrared structural map of the building,” she said while setting up her gear. “This building is weird. Normally, there should be at least 2.7 meters of vertical space per floor. But…” — she traced her finger along the blueprint — “between the twelfth floor and the roof, there’s an unexplained three-meter void.”

Lin Mo narrowed his eyes. “You’re saying the thirteenth floor… might be hidden between two layers?”

“Exactly. But not in any conventional sense.”

They stepped into the elevator. Jiang Yan discreetly attached a signal jammer just beneath the panel.

“This will let us override the default programming,” she said.

The elevator began to ascend.

1… 2… 3…

As expected, there was no “13” on the panel. But just as the floor indicator jumped from “12” to “PH,” Lin Mo caught a flicker — a brief flash of the number 13.

“Now!” Jiang Yan shouted, pressing the emergency stop.

The elevator jolted violently, then came to a halt. The doors remained shut. The screen above them glitched, alternating between “12” and incomprehensible symbols.

“We’re in the gap,” she whispered.

Lin Mo pressed his ear to the elevator doors. Faintly, almost imperceptibly, he could hear it — drip… drip… drip…

Without thinking, he hit the open button.

The doors creaked open.

They were staring into a dim corridor that looked nothing like the rest of the building.

The walls were stained, peeling, soaked in dampness. The floor felt soft and uneven underfoot, the air heavy with the scent of mildew and rust — a space forgotten by time itself.

At the far end, a door stood slightly ajar, a weak, flickering light emanating from within.

“Stay sharp,” Jiang Yan muttered. “We’re going in.”

Their footsteps echoed against the wet floor, the sound eerily muffled. Each door they passed had an old-fashioned red paper slip taped to it, marked with names in faded ink: Wang Zian, Li Yulan, Duan Weixin…

“These names…” Lin Mo whispered. “I saw them in the files. They were the ones who reported hearing strange sounds… just before the building was supposedly sealed.”

Jiang Yan nodded grimly. “Maybe they never left.”

Just then, the door at the end creaked fully open.

Inside was a decrepit living room. Water dripped from the ceiling, soaking through rotting furniture. A large mirror hung crookedly on the wall, reflecting both of their figures — but with no faces.

Lin Mo’s heart skipped a beat. He turned around instinctively — no one behind them.

Then a third shape appeared in the mirror. Faint. Motionless. Standing directly behind him.

“Go!” Jiang Yan shouted, grabbing his arm and pulling him toward the hallway.

At the end, a narrow beam of light shone from above. They lunged for it just as the door behind them slammed shut.

The elevator — it was there again.

They collapsed into it, breathless, drenched in cold sweat.

Jiang Yan hit the return button. The elevator rumbled upward, slowly, reluctantly.

When the doors finally opened at the twelfth floor, the familiar hallway stretched before them like a lifeline. For a moment, they just stood there, dizzy with relief.

“That wasn’t a floor,” Lin Mo said quietly, almost to himself. “It was… a memory. A phantom left behind by people trapped in the echo of time.”

Jiang Yan inhaled sharply. “We have to go back again. But next time… we find the source. The origin of the echo.”

Lin Mo clenched his fists. His gaze was steady, burning with resolve.

“13F isn't just a hidden floor. It's a place abandoned by memory. And we’ve already stepped across its threshold.”

Later that night, his phone buzzed again.

A message, from “13F.”

“Welcome back. You’re on the list now.”

Lin Mo stared at the screen, finger hovering over the delete button — but he didn’t press it.

Because deep down, he knew —

The game had only just begun.