The 8-B-3 Sealed Door Was Twenty Centimeters Lower Than the Blueprint

8-B-3 sealed door was twenty centimeters lower than the blueprint.

Dohyeon measured the difference first. The blueprint listed the height at one hundred eighty, the actual at one hundred sixty. It meant the slab above had sagged since the closure three years ago.

"Entry posture changes." he said. "The point person bends at the torso. Bending brings the line of sight to the floor."

"Then I can't see ahead." Saebyeok lowered her shield.

The lowered shield was the same one she'd used at yesterday's evaluation site. The folded lower edge was unchanged, and that angle fit the low doorframe better.

"I'll see ahead with sound."

11:40 AM. Re-entry approval came as a conditional continuation license, and the condition was two hours.

Yura was outside. If an unregistered person was added to the entry roster, the license would be suspended on the spot, and that clause was attached to yesterday's evaluation results.

Instead, Yura was holding one item from the preparation list. A procedure to prevent someone from going unfound without a name. The method was still blank.

"What do I write down today?" he asked.

"Who went in at what time and came out at what time." Dohyeon said. "If three go in and three come out, that's three lines. If one doesn't come out, the item starts working from that point."

The eighth oxygen tank was issued under Baek Seonho's own name. This was the third unnamed prescription this month.

Three times meant suspension. Baek Seonho issued it knowing that, and left Eunchae a single sentence. After today, find someone else.

The entry order followed what was written on paper yesterday. Saebyeok at point, Igyeol beside her observing for halt calls, Dohyeon at the rear taking measurements. Mirae ten steps outside the door.

"Two contact signals mean rotation." Saebyeok confirmed. "What does three mean."

"Three wasn't decided." Dohyeon said.

"Then we decide now. Three means everyone withdraws."

"Why decide now." Dohyeon asked.

"I learned yesterday." Saebyeok said. "If it's not written down, it didn't happen."

Igyeol wrote it on the paper. One more clause had been added before entry.

The passage was dry concrete for six steps. On the seventh step, Dohyeon's foot made a different sound.

An empty sound.

Dohyeon stepped on the spot again. The second time was the same.

"Halt." he said.

The three of them stopped. Dohyeon bent his knee and pressed the back of his hand to the floor. There was a vibration. It wasn't coming from above but rising from below, and it had a rhythm.

"Two point two seconds." he said. "Same period as the wall at yesterday's evaluation site."

"So there's piping here too." Saebyeok asked.

"I don't know. Only the period is the same." Dohyeon said. "The same period isn't the same cause."

"Then what do we need to check."

"Thickness." Dohyeon lifted the measuring device.

Dohyeon pressed the device to the floor. His own unit was confiscation list item number nine, this was an old model he'd borrowed yesterday. A single value appeared on the screen. Uniform thickness.

"The sensor says uniform." he said. "This model doesn't give a margin of error. That's also a problem."

"What do my ears say." Saebyeok asked.

"They say it's hollow."

"So which way do we go today." Saebyeok asked.

"I'll check once more." he said. "I threw out the sensor yesterday too. Twice in a row, and that's my habit."

Dohyeon shifted half a step and pressed again. Same period. And three steps ahead, the same period sounded again.

The stretch was long. Not a localized void.

"It seems like the next ten steps are all hollow." he said. "Confidence is seventy percent."

"Do we go in at seventy percent."

"Yesterday we went in at fifty four."

"That was a mannequin."

Saebyeok pulled her shield back half a span toward the doorframe. It was a calculating motion. Behind her was open, ahead was probability.

That was when the floor folded.

Sound came first. The two point two second period shortened to one point four, and Dohyeon was the one who heard it. Before he could speak, Saebyeok moved.

"Stop."

Saebyeok said those two syllables while already striking Igyeol's back twice. Word and hand at the same instant.

The floor sank fifteen centimeters across a width of three steps ahead. Dirt fell downward, and cold air rose from where it had fallen. It was a sign that empty space existed.

Igyeol's left foot caught in the sunken spot. It sank to the ankle, and her knee buckled. Saebyeok's shield came in behind her back and held her torso upright.

Saebyeok counted three breaths. During those three, Igyeol's foot pulled free.

Igyeol stepped back twice. She didn't ask why.

"Dohyeon." Igyeol said. "Command transfers to you."

"Received."

The exchange ended short because it followed the order written on paper yesterday. The handoff took two seconds, and during that time the floor dropped another five centimeters.

The first thing Dohyeon did was count. Three people, thirty four minutes of oxygen remaining, seven steps to the door.

Until yesterday, he would have produced three possible values in a spot like this. Now he produced only one.

"Everyone withdraw." he said. "Saebyeok, give three contact signals."

"Only the front three steps collapsed." Igyeol said. "The remaining five steps haven't folded."

It wasn't opposition. It was information. Dohyeon received it and still held to his own judgment.

"I haven't measured the period of the remaining five steps." he said. "We don't go into a stretch we haven't measured."

Igyeol backed off. It was the same kind of retreat she herself had made at yesterday's evaluation site.

Saebyeok struck Igyeol's back three times. The clause they'd made twenty minutes earlier was used for the first time.

The withdrawal order wasn't the reverse of the entry order. Dohyeon changed the sequence.

"Saebyeok goes last."

"If the point person goes last, the shield can't cover the front."

"It's not the front, it's above. What's collapsing right now is the floor, and if the floor drops, a person goes down. A shield can't block below. Instead it blocks what comes down from above."

Saebyeok took in the calculation. She moved her position backward.

It took eleven seconds to come out of the seven steps. On the last two steps, Saebyeok's body stiffened. A collapse sound had actually occurred.

It was three point two seconds, and during that time her hand pressed the glove's velcro twice.

Dohyeon counted it. Counting, he didn't reach out his hand. If he reached out, he'd be entering the passage himself.

"Two steps to the threshold." he said. "If you can't see now, come toward my voice."

Saebyeok's feet moved. Two steps came.

The three of them stood outside the door. 12:06 PM, twenty six minutes since entry.

Nothing had been recovered.

Yura wrote three lines from her spot ten steps outside the door. 11:40, three entered. 12:06, three exited. The third line held three names.

"Is this right?" he asked.

"Right." Dohyeon said. "Today that item didn't activate."

"I'm recording." Dohyeon said. "Twenty six minutes of entry, all three entrants recovered, zero materials secured, zero injuries. Halt orderer Yun Saebyeok, command transferred from Han Igyeol to Im Dohyeon."

"There's no result." Mirae said.

"That's the results column." Dohyeon said. "I'm looking at the people column. Three went in, three came out."

"Does that column go into the evaluation." Mirae asked.

"It doesn't." Dohyeon said. "That's why I write it in my own log."

Igyeol opened her notebook. What she wrote today was two lines. One clause, and the time of the halt.

"Do we go in again." Saebyeok asked.

"We go in. After we get floor support equipment." Dohyeon said. "That won't come today. With a grade 1 account, the rental queue is four days."

"Gyeongmin's grade."

"Yes. The grade he lowered himself yesterday."

Saebyeok took in that calculation. One act of honesty yesterday had become four days today, and no one said they regretted it.

With two steps left to the threshold, a sound came.

Three times.

The intervals were even. Not a palm but a fist, striking metal piping. It was the signal maintenance workers used to announce that someone was inside a zone, and Dohyeon had learned it while counting subcontractor equipment lists.

He looked at Saebyeok. Saebyeok had heard it too.

Three came again. The interval was the same.

Dohyeon wrote down the time. 12:14:08. Recording down to the second started today.

"This is one sample." he said.

"If it comes once more."

"Then it's two."

The third signal came. Dohyeon wrote the second. The interval from the previous signal was twenty four seconds.

"Twenty four seconds." he said. "Both times, twenty four."

"What does that mean."

"A person." Dohyeon said. "A machine doesn't vary. This is a person with enough strength left to knock once every twenty four seconds."

Saebyeok took half a step toward the sealed door. She hadn't raised her shield, and the hand that hadn't raised it touched the door.

"Do we go in." she asked.

"We can't." Dohyeon said. "The floor has folded. If we go in now, we go down. And then we fall on top of whoever is below."

Saebyeok took her hand back. There was no number that could overturn that judgment.

"Then what do we do."

"Answer." Dohyeon said.

He struck the piping beside the sealed door three times with his fist. He matched the interval to twenty four seconds.

Three came from inside. This time the interval was twelve seconds.

"It shortened." Dohyeon wrote. "It means they heard us."

Mirae took a photo of the time. 12:21, one photo of the piping. The sound waveform couldn't be preserved. The recording equipment was also on the confiscation list.

"Then this signal was heard only by the four of us." he said.

"Three." Dohyeon said. "Yura is ten steps outside."

Yura heard that and walked over. Pulling the oxygen tank, she came up to six steps away, and stopped there.

"I can hear it from here." she said.

Dohyeon and Saebyeok looked at her at the same time.

"Then it's four." Dohyeon corrected what he'd written.

At the corrected line he added one more. Four witnesses, one of them unregistered. The value of the testimony split at that line, and Dohyeon wrote down even the fact that it split.

"Will this line become a problem later." Yura asked.

"It will." Dohyeon said. "Your testimony carries little weight in court. So it's more advantageous to count only three of the four."

"Then write it as three."

"I won't." Dohyeon said. "If you count in whichever way is advantageous, that's not measurement."