The Fifth Chair

Kang Mijin said to seal off desk 4 with plastic sheeting.

Baek Dowon said someone had to follow the line under that desk.

Both were trying to keep Im Seoha alive.

Follow only one, and the other risk would land first.

The anonymous call had already ended. The handset screen still showed no caller, no number. When asked for an address, the voice had only answered "desk 4," and that was all Yuna's recorder had. The open ticket still read count 3 seconds, handler 4721.

Mijin pulled clear protective sheeting from the supply closet and split the job into three pieces.

"Seoha, step two paces back from your seat. Yuna, bring out only the laptop with the evidence. I'll seal off the area around desk 4. Phone, printer, chair, all at once."

Yuna didn't take her hands off the keyboard. The hash check on the offline folder she'd built to dodge the delete command wasn't done yet.

"If I pull the laptop I can't cross check the printer sound timestamps."

"Cross check it alive, then."

Dowon's voice cut in over the radio. He'd finished the site response and was standing at the building's exterior comm box.

"Don't seal it. The external line's disconnected but a call still came through. Another line's ringing under the desk. Cover the inside and we lose the location."

"So while you're inside chasing that line, who does the handler status jump to?"

"Just don't sit down."

"And how did you confirm that?"

They were talking to each other but looking at different dangers. Mijin wanted to seal off the space between the person and the seat. Dowon didn't want to lose the thread between the phone and the building. Neither of them was afraid without reason. That was exactly why it wasn't easy to choose.

Seoha drew two lines on the back of the paper shift schedule.

"Failure conditions for the containment first."

Mijin set down the roll of plastic.

"Stop if Seoha's name erases further, if another employee number shows up on the ticket, or if the chair moves."

"Failure conditions for the line trace."

Dowon answered by striking the comm box's steel panel twice with a wrench. After the confirmation tone came a short breath.

"Stop if the line moves inside the wall, or if the phone sound and the vibration don't match. I don't cut it."

"Three minutes." Seoha wrote it down. "Chief Mijin watches my status and the desk boundary. Dowon only traces the line from the exterior comm box to under the desk. Yuna cross checks the two timestamps with the offline log. Both of you stop after three minutes."

The printer spun an empty roller once. The end of the sheeting in Mijin's hand got pulled toward the desk. There was no wind. The plastic, not even taped down yet, wrapped itself around the corner of the phone.

Yuna got pushed back from her chair, laptop clutched to her chest. "Meeting adjourned automatically, I guess."

Mijin yanked the plastic taut and pinned it to the floor with her knee. "Faster to just tape this down than hold a negotiation."

"That just came close to a containment failure condition. Something moved." Seoha logged the time. 00:43:06. "The point is not to lose the other evidence if one of us turns out wrong."

Yuna hugged the training laptop to her chest.

"I'm in favor. We can save the possibility that both of you are wrong too."

Mijin didn't smile. Instead she took off her wristwatch and handed it to Seoha. Handing over an object meant handing over a deadline, one that would stop her too when time ran out.

"Until 0:46. After that, we do it my way."

The sound of Dowon coming up the emergency stairs reached them before the radio did. His safety boots struck the metal steps twice on every landing. He didn't come through the center door. He knelt at the corridor's inspection hatch instead. Seoha and Yuna watched him through the doorway.

"Under desk 4. Don't touch it, just open the cover."

Yuna pushed a long ruler under the desk and lifted the latch on the cable cover. The existing power line and phone line were labeled. Underneath them was one more line, flat and black. It wasn't on the building's construction drawings, and it wasn't on the asset list Yuna had pulled.

The surface of the line had no dust on it. But the cable groove it seemed to run through was caked with old gray dust all the way to the edges. It didn't look like a new line had taken over an old spot. It looked like the spot was insisting it had belonged to this line all along.

"It looks brand new. Like it was just laid down." Yuna said.

"Don't just say it, check it."

Dowon set the tip of a screwdriver against the inside of the hatch. Seoha opened the recording waveform on the laptop. When the printer roller struck the empty tray, the black line trembled once.

Click.

The same tremor traveled up through the handle inside the hatch.

"First channel. Physical vibration." Dowon said.

"Not the second one yet." Seoha held him back.

Just then the containment tape Mijin had laid lifted a hand's width off the floor. It wasn't that the chair inside the tape had moved. The tape itself had redrawn its line toward the chair's legs. Mijin didn't rush to close the sheeting. She pulled the tape's starting point back to line up with the wristwatch's position. Containment might be an act that chose its own target.

"The boundary isn't choosing the desk. It's choosing the chair," Mijin said.

"Don't make that call yet. It moved once."

Before Seoha finished speaking, Dowon caught the black line lightly between his thumb and forefinger. He didn't cut it, didn't pull it. At that moment phone 4 rang.

Dowon's voice came out of the speaker.

"Don't touch it."

In the corridor, the real Dowon kept his mouth shut.

The voice on the phone spoke again.

"Never mind, just cut the line."

Dowon's face hardened first. It was the kind of thing he'd normally say, but the action tacked onto it was wrong. Dowon never told anyone to cut a line before confirming the site.

He let go.

"That's my voice. Not my order."

Mijin froze with the sheeting half unrolled. Handler 4721 stayed unchanged. Seoha's name on the paper shift schedule was still intact. No containment failure condition had triggered.

Yuna checked the call timestamp.

"Printer roller, 0:44:18. The call went out at 18 seconds. Same second for the vibration too."

"External line?" Seoha asked.

Mijin held up the paper cup. The gray cable end was still sitting inside it.

"Still disconnected."

Dowon followed the black line from the hatch. It didn't run straight into the wall. Every time he took a step, the bulge under the cable cover shifted at the same pace. Like someone matching his steps from the other side of the corridor.

"The line's moving."

"That's a trace stop condition," Seoha said.

Dowon's hand went into the hatch one more time. The tip of the wrench pressed against the black line. The line slid away from the tool, toward the wall. The back of his hand scraped against the edge of the cover and drew blood.

Mijin let go of the sheeting and started for the first aid kit. Dowon set the wrench down first.

"Don't come. This stops here."

He taped a thermometer three panels ahead of the hatch and marked the direction of movement in chalk. Instead of chasing it, he left a trail. In exchange for reining in his own charge, the black line vanished inside the wall.

Mijin didn't fully close the sheeting either. She left one opening between the desk and the people, and stuck the end of the tape down next to the wristwatch.

"Leave the vents and the cable cover open on the containment side too. We're not shutting them in somewhere we can't see."

When the three minutes were up, neither of them had won. Instead, without any external line, the printer, the black line, and the phone had all acted in the same second, and the Dowon on the phone hadn't been able to mimic the real Dowon's actual principles. For the first time, the sound from the scene and Yuna's offline timestamps landed on the same line.

Seoha wrote on the back of the shift schedule: Hypothesis, desk 4's address connects not to an external line but to the printer's internal operation. She didn't write "rule."

The cut on the back of Dowon's hand was shallow, but chalk dust had stuck to the blood and clumped gray. Mijin only pushed disinfectant and gauze up to the threshold of the corridor. She didn't pull him inside until he wrapped it himself. She wasn't going to let the boundary between containment and tracing make the decision for a person instead.

"I'll keep the duplicate folder open," Yuna said. "Chief Mijin, you check Seoha's log. Dowon, just add your chalk positions. Nobody overwrite each other's files."

Mijin raised an eyebrow.

"Did you just assign me a task?"

Yuna unclipped the USB from the desk and hung it around her neck. "Yes. Lowest grade temporary authority there is."

Right after the joke, her hand started shaking. To hide it, instead of straightening the keyboard, Yuna spoke to Seoha.

"I think I'll get the count wrong if I do it now. Can you help me check the items."

Seoha didn't count for her. "Let's do it your way. I'll cross check."

Mijin pulled a chair over to make room for Seoha to sit just outside the sheeting. Then she stopped moving.

There was one extra chair inside the containment line.

Row 4 of the center had always had four chairs. Seoha didn't say the number out loud. She didn't go looking for a name either. The new chair sat neatly beside desk 4. Its faux leather backrest was blacker than the other chairs, like it was still new, and the seat had not a single drop of moisture on it.

Only the wheels had just been wiped clean.

Mijin's lips moved.

"Current staff on shift is four."

She swallowed the rest of the sentence. She chose not to say the total of empty seats.

"Let's confirm with objects, not headcount," Yuna said first.

Seoha set down her employee badge and the 00:17 printout. Mijin set down her wristwatch and the paper cup. Yuna set down a white keycap she'd pulled off her keyboard and her USB. Dowon, still in the corridor, didn't step past the threshold. He set his wrench and radio down side by side on the floor.

Before anyone touched anything, Yuna photographed the entire floor with the training laptop. The shutter sound went off. Dowon's radio buzzed briefly on the floor. He reflexively picked it back up. He didn't press it. The wrench stayed where it was.

"Position change. Dowon's radio, off the floor, in hand," Yuna logged out loud.

That was the last set of objects the four of them had actually handled themselves.

There was nothing in front of the new chair.

Yuna pulled up the photo she'd just taken and entered each item into the offline list. Employee badge, printout, wristwatch, paper cup, keycap, USB, wrench.

Seoha cross checked the list against the floor again.

Dowon was holding the radio in his hand.

All three of them had seen him pick it up, and Yuna's spoken log had recorded it too.

But in the photo taken just before he set it down, only the wrench was there.

The radio wasn't on the list either.