The Thirteenth Hold Tone

The hold music was always twelve bars.

That day there was a thirteenth bar.

After it came Nam Sangho's voice.

Im Seoha did not say his name.

Of the three tickets addressed to the closed Northwest Fourth Pressure Pump Station, the middle line blinked first. The handler field was empty, and the call monitor showed no caller number, only a status that read `verifying on site`. Yuna had kept the speaker output and the recording file separate. If the same sound entered both files at once, it wasn't independent evidence.

Seoha did not press play. She opened the standard hold track first. The company's standard audio looped back to the start after twelve bars. On the speaker right now, after the twelfth bar ended, three low keyboard notes followed. Too short to call a song, but too rhythmic to call a glitch.

Yuna counted the notes on her fingers. "Thirteen. Exactly one extra bar."

Mijin set down her cold coffee. The bottom of the cup covered one empty line on the paper shift schedule. She moved the cup right away.

The extra bar ended.

"Anyone there?"

That was the question Nam Sangho always asked first on the field radio. The voice matched even down to the hoarseness. Seoha's hand stopped, still searching under the desk for her safety boot laces. She already knew what would come first if she answered the voice.

She did not say that name.

"Pump Station Four, Valve Three. Which way do you turn the handle to close it?"

A sound of inhaling came from the speaker. Mijin's hand gripped the coffee cup tight. Yuna wrote `did not ask sender's name` in the log and attached the time.

"Clockwise."

Seoha spread out the facility diagram next to the old wiring plan. Beside Valve Three on the diagram, the same answer was printed. Too easy a match. Anyone who had read the company files could have given that answer.

"What color is the handle?"

"Red."

The diagram said crimson. Mijin opened her mouth, then closed it. Only two details had matched so far.

Seoha chose the next question. "Which tool do you use first when it's closed in winter?"

"Hex wrench. Loosen half a turn, clockwise."

Dowon's voice cut in on the wiring room radio. "Wrong."

The breathing on the speaker stopped.

Dowon said, "Valve Three is reverse threaded. The diagram was never updated. Counterclockwise. Use a wrench and you'll snap the shaft."

A moment later, a low curse came through the speaker.

"Baek, you still haven't replaced that sheet? Valve Three is counterclockwise. If the handle's frozen, hit the bottom twice with a rubber mallet. Put a wrench to the shaft and even overtime pay won't cover it."

Dowon's radio went quiet. That sentence was the correction Nam Sangho used to make every winter inspection. Even the habit of putting wrench costs and overtime pay in the same sentence matched.

Mijin whispered, "Only Sangho would say that."

Seoha raised her palm, not to cut her off, but to slide the empty log field toward Mijin. Mijin didn't finish her own sentence. Instead she wrote `matches the correction phrasing Sangho used`. She added `caller` in front of `Sangho`.

Possibility the caller is Sangho.

Not confirmed.

"What sound is coming from near Valve Three right now?" Seoha asked.

The speaker didn't answer. Only an uneven tapping on metal came through. Two short, one long. Similar to the interval the three P-17 strands had trembled at in chapter six. Mixed in behind it was the sound of water forcing its way backward up a narrow pipe.

Dowon moved the vibration meter in the wiring room. Through the radio came the sound of a plastic case touching the floor.

"P-17, second line. Two short, one long."

Yuna laid the speaker waveform and the timestamp of Dowon's radio side by side. The call side was 0.8 seconds ahead. If it were the same recording fed back, the office output should have lagged. That wasn't proof the caller was at the pump station either. There was still no known path for a signal to reach the center before it reached the wiring line.

"One more matching detail. Current sound matches." Yuna said. "One mismatched detail too. The call is faster than the field line."

"Still unknown," Seoha added.

Yuna split the ledger into three columns.

Matching details. Mismatched details. Still unknown.

In the first column she put the reverse thread, the two mallet strikes, the overtime pay phrasing. In the second she wrote the 0.8 second gap between the call and the field vibration. In the third she left the caller's authenticity, the actual location, and who had made the sound first.

Mijin couldn't drink her coffee. Every time the extra bar started again, a small ring formed on the cup's surface. She wrote down times instead of feelings. First extra bar 01:47:12, correction phrasing 01:49:03, field sound crossover 01:50:26.

The voice came through the speaker again.

"Seoha."

Yuna's hand froze over the keyboard. No one had asked for a name. The caller had said the name first.

The left border of the middle ticket, the one holding the call, flashed white first. The light climbed one row up the line divider and stopped at the first ticket's handler field. Only then did `Seo` appear in the empty box. The screen showed, in order, the call jumping to a different row.

Yuna didn't press the screen recording button. If it was the system's internal recording, the row transition time could shift along with it. Instead she stood an offline phone in front of the monitor, lining up the three lines she'd drawn on paper with the three rows on screen so they fell in one frame. Middle row flicker 01:51:08, first row transition 01:51:09, handler fragment display 01:51:10. The printer pushed out a blank sheet three times, half a line each, in the same order.

The row transition had been observed. Whether the name had become a new address, that was still unknown.

Yuna didn't turn off the monitor. She just stood a piece of paper up in front of the first row to block it. She wanted to hide the name fragment from the screen without destroying the original.

"Don't answer." Mijin's voice stretched out. "No, wait, you have to answer, just not the name. Only what's needed right now."

Seoha didn't answer to her own name either. "How many floor tiles from Valve Three to the entrance door?"

"Sixteen."

Dowon objected immediately. "Eighteen, after the construction before it closed."

The voice didn't laugh. "The diagram says sixteen. Right now it's eighteen. The last two tiles aren't gray, they're yellow. They tore up the floor and then couldn't afford to match the tile."

Dowon pressed his radio button twice. Whether it was a signal of agreement or a warning, Seoha didn't ask.

"Do you have a photo of the site?"

"Under my toolbox. Can't see inside the door, it's flooded."

That was the first sentence that sounded like a present location. That there was water flooding inside the pump station door. But that too could be mimicry, drawn from an old inspection record.

Yuna said, without any joke in her voice. "Dowon, I need the original site photo. Creation timestamp and lens scratches included."

"I'll go up to the wiring room and check the toolbox."

"Don't go alone."

Yuna kept the request to one sentence. Seoha didn't put that sentence into the log. Instead she sent her employee badge and her own radio up the wiring room stairs with Mijin. Mijin went out the door to meet Dowon. It wasn't a setup where the two of them moved together while leaving Yuna as the one to protect. Yuna took the role of holding down the originals and the signal at the center.

After Dowon went up, he opened the old toolbox. On the underside, a site photo with peeling lamination was taped. From Valve Three to the door, eighteen tiles, including two yellow ones. In the corner of the photo was the blue sealant stain that always got on Nam Sangho's thumb.

The photo didn't prove present water. But it became a second physical piece of evidence that the voice knew the tile count after the most recent construction.

Yuna didn't scan the original photo. Lens scratches and the sealant stain could be smoothed away in the copying process. Instead of a screen capture, she put the photo itself into a clear plastic sleeve and wrote the observation time on top of it.

"Possibility of Sangho going up."

Seoha said, "Authenticity still unconfirmed."

"Right. Location still unconfirmed too."

Neither of them took that sentence away from the other.

The call went quiet. The thirteenth bar of the hold music repeated three times. That was when Hyeonju's tablet call popped up on the center screen.

"End the call. The closed facility address will be sealed under exception authority."

Mijin lowered the speaker volume. She didn't turn it off. "If we seal it, it moves to the next facility."

"Protecting current center staff is the priority," Hyeonju said. "Guessing the caller's identity is not grounds for a rescue."

"Correct." Seoha pulled out her safety boots. "That's why we won't dispatch based on identity. We'll confirm it with the current pipe sounds, water level readings, and the tile information."

Dowon chose a rubber mallet and a manual water level gauge instead of a cutter. He set each tool down on the floor one at a time and said, "I'll look at the door first. Seoha logs time from outside. No touching the valve until we've confirmed the water inside."

"No going in alone."

"That line, put it in the report this time too."

Seoha didn't write the two names in the dispatch field. She wrote only employee numbers and roles. Site check 4721, wiring and valve check 3184. Until she'd confirmed whether a name could become an address, she wouldn't put names in the call notice.

Yuna entered her own employee number in the center remaining field. The gray candidate border stayed the same, but she didn't take her hand off it. "I'll hold the original logs. Requesting this without any jokes. Every four minutes, each of you tell me one object you're holding."

"What object?" Dowon asked.

"Whatever's in your hand right now. And your next move."

Seoha held up her radio. "Radio. Battery sixty one percent. Next, checking the entrance twice."

Dowon held up the rubber mallet. "Mallet. No cracks in the handle. Next, knocking on the door."

Mijin decided to stay at the center to log the call with Hyeonju. She didn't throw out her cold coffee, just wrote 01:57 on the cup lid. No laughter, no mention of overtime pay.

Seoha's hand, tying her safety boot laces, stopped.

The hold music cut off on the speaker.

"November 6, 2019, 02:14:38."

Seoha knew that time. It was the moment she had pressed the completion signature on Nam Sangho's field departure report. A timestamp down to the second, erased from the original and not even left in the training copy.

The voice said,

"You signed that, didn't you."

Seoha didn't drop her pen. Below the dispatch log she wrote the time once more.

02:14:38.

Beside it she wrote, `sender path unconfirmed`.