43 Minutes of Oxygen Left

43 minutes of oxygen left did not sound like a number. It sounded like someone breathing. Inside the emergency control room a child pushed the oxygen mask away, and a nurse pressed the strap back down with the back of her hand. The needle on the pressure gauge trembled between 2.1 and 2.0. Every time it dropped, the voices on the hospital radio dropped with it.

"Six in the ICU, twelve in the ER, three in recovery. Going by the central oxygen alone, that is 43 minutes."

The doctor wrote the patient counts on a white board. The networked clock read 07:19. The wall clock read 07:12. My wristwatch hesitated at 07:11 and then moved to the next second.

"Let's separate the time sources first. Network, wall clock, wrist, equipment panel."

"There's no time to be syncing clocks."

Jang Yura pointed toward the patients. "Not syncing them. Deciding which one we trust when we open a valve."

The doctor set down her pen and looked at the gauge. "By the equipment panel it's 45 minutes. By the cylinder inventory it's 37. If one more critical patient goes up on oxygen, it drops under 30."

"Then where does 43 come from?"

"Central oxygen remaining, averaged over the current patient count."

"You can't move people on an average. Start with the room that drops fastest."

Jang Yura turned the board around. The doctor paused, then wrote a room beside each patient number. ICU, recovery, ER. Once the numbers had places attached, the orders changed. The manual cylinders stacked up in front of the ICU first, and a nursing assistant was posted in recovery instead of a family member.

I wrote at the top of my notebook. Oxygen timer basis: average, 43 minutes. Varies by room. Do not use network time alone.

Out in the corridor beyond the control room, families were forming a line in front of the ward doors. It was not an evacuation line. It was a line to watch who got a cylinder first. When one person said "my mother goes first," the person beside her held up a patient wristband. Jang Yura walked in between them.

"Don't give me names. Give me the room number and the oxygen method."

"Why can't we say names?"

"Names turn this into a fight. Methods turn it into an order."

She did not shout at them to step back. Instead she tore off floor tape and laid down three lines. Spontaneous breathing, supplemental oxygen, manual ventilation. When the medical staff called a patient's status, the family moved behind the matching line. The feeling in the corridor did not shrink. It just stopped grabbing at the staff's arms and grabbed a line on the floor instead.

Watching it, I folded the list again. The list had only names on it. What we needed now was not a name but a method. Not who had been scheduled to die first, but who could not last five minutes without a specific piece of equipment.

O Gyeongtae spread the facility drawings on the floor. The dust he had breathed in at Myeongjin Station brought on a short burst of coughing. He covered his mouth with the back of his hand and pinned the corner of the drawing under his shoe.

"If the automatic valve seized shut, the pressure inside the reservoir is still there. The problem is it can't reach the ward line. Manual bypass is here."

He scratched at the lower part of the drawing with a pencil. It was a zone shaded in red.

"Access rights?"

"Normally central control. Right now you open a door and turn it by hand."

"Where is the door?"

O Gyeongtae stopped the pencil tip. "North side of the facility floor. Behind the red fire door."

The smell of burning metal scraped the back of my throat. A red door. The light of an explosion. Someone turning a handle. That memory was not from a report. It felt like something I had seen myself, but the order of it had been cut away. The kind of trauma fragment I wanted to grade A. The color of the door was certain. The conditions were blank.

"That door must not be opened."

Jang Yura asked at once.

"Why?"

"There's an explosion in my memory."

"Not memory. Conditions."

I could not answer.

The control room door opened and a student came in wearing a small backpack. A hospital visitor pass hung crooked over her uniform. In her hand was a clear case the size of a palm. Inside it, a small second hand moved on its own.

"Who's in charge here? My grandmother's in recovery on the fifth floor, and all the hospital clocks are lying."

When a security guard moved to stop her, Jang Yura raised a hand.

"Name."

"Seo Minchae. Robotics club. No, that's not the point right now, the point is this clock is the only one that's right."

Minchae set the case on the table. Through the clear lid I could see a crystal oscillator module and a battery. The solder joints were not clean. Tape was holding one side together.

"Phones are about 7 minutes fast. The hospital panels are all over the place. But this one matched the offline log from the subway station office. I didn't exactly eavesdrop on you adults just now, the log times came over the corridor announcement. So I mean, I did eavesdrop, but..."

"Did you hack anything?"

"No. I can't hack. I don't even know the hospital wifi password. It's just weird that this clock is the only one not drifting."

I looked at Minchae's hands. There was black dust under her fingernails. Not dust picked up in a hospital corridor. Those were hands that had been opening and closing small devices for a long time. Inside the clear case a strip of tape carried a date. `Club competition spare`. It was not something she had thrown together on the spot.

"How did you verify it?"

"Two phones, three hospital wall clocks, one information terminal. They all disagree with each other. I set this one last night and haven't touched it since. And I compared it against the offline second hand caught on the Myeongjin Station rescue video. The video is the original, from the radio account."

"Did you confirm it was the original?"

Minchae started to answer, then stopped. "No. I mean, the file that's labeled original. Ah, that sounds bad. I only looked at the label."

Seojin cut in from the other end of the phone. "I uploaded that file. It is the original. I'll send the hash."

Minchae's eyes went wide. "Wait, Han Seojin from the radio? I subscribe to your..."

Jang Yura held up a finger. "No fan greetings right now."

"Okay. No fan greetings."

Minchae opened her mouth once more anyway and closed it. The clock she had brought was not a toy, but she did not know the language of a scene yet. A good tool and good judgment are two different things. People who do not know the difference cause accidents the same way, adult or child.

"If the clock is right, what does it change?" I asked.

"It lets you time the moment you open the valve. Even if the central command jumps, this doesn't. And if I measure the 41-byte repeat interval with it, I can separate out the network delay, and..."

"Packet tracing is on hold."

"Why?"

"Patient oxygen comes first."

Minchae did not argue back. She looked at the clock again instead. "Then this clock goes on the valve, not the packets."

Once its purpose changed, the object came inside the scene.

O Gyeongtae picked up the case. "Crystal oscillator, so it isn't tied to the network, it keeps its own beat. Kid talks fast, but the hardware's usable."

Minchae corrected him immediately.

"Whether it's usable isn't verified yet. It's only drifted less for 20 minutes."

I wrote in my notebook. Seo Minchae. Not on the list. Offline crystal oscillator clock. Current observation B. No future memory.

People who were not on the list were dangerous. Not because it meant my memory guaranteed nothing about them, but because they walked in carrying a present-tense choice that nothing had been taken from yet.

A second file came from Seojin. This one was raw audio recorded outside the hospital radio room. The 41-byte repeat was sharper. The short pattern scraped through the gaps between the oxygen alarms at a steady interval.

Seojin spoke over the phone.

"I'll try to pin down the transmit location. The strength is higher inside the radio room. This isn't just noise."

The ICU radio broke in. Oxygen saturation 88. Prepare manual bag. Central oxygen pressure falling.

Two pursuits opened at the same time. Follow the pattern and we could find the source of a signal none of us had seen before. Go to the ICU and we could hold onto a breath that was dropping right now. I looked at the name of Seojin's file and then shut off the screen.

My reason for wanting to chase the pattern was clear enough. The 41 bytes might have come from the future. It might be the same family of thing as the white screen I saw in the control room just before I died. But that was an assumption. The hand of the child pushing away an oxygen mask was not an assumption.

"Just preserve the raw audio. Tracing is on hold."

"Igyeom."

"Patients first."

"I'm putting that on the record."

Seojin did not ask again. She sent the radio room's location and the state of its door instead. The door was open, one staff member inside. The transmitter was powered on but external broadcast was suspended. What she could do was not tracing but preservation and sharing her position. That boundary had to exist. When a reporter opens every door, the rescue team ends up with more doors it has to close.

Jang Yura said on her way out of the control room. "Good. Oxygen for now. Seojin, in the radio room, just hold the original. Don't go in alone."

"Is that an order?"

"It's a field request. Refuse it and you keep telling me where you are."

After a short silence Seojin answered. "Turning on location sharing."

The stairs down to the facility floor were wet. Water dripped from the ceiling one drop at a time, coolant or rain, no way to tell. Every time O Gyeongtae took the rail he spread his fingers and closed them again. The hand he had hurt at Myeongjin Station was late following him.

"Grandpa, I mean mister, can I put this clock here?"

"If you'd said grandpa I'd have told you to carry it back upstairs."

"I said mister."

"I heard you."

Minchae shut her mouth and held out the clock. O Gyeongtae stuck the case under the panel beside the door. The tape peeled off the wet wall once and then held after Jang Yura pressed it down with her glove.

"Battery?"

"Six hours on the clock. Under 40 minutes on the robot. Less if water gets into the wheels."

"We aren't using the robot yet."

"Right. Not yet."

Minchae repeated `yet` back. There was hope mixed into it, but her hands went into her pockets. Not taking something out was a role too.

The red door was at the bottom of the stairs. Old paint had flaked away, showing bare steel through the gaps. A `Do not open` sticker was half torn off. A low tremor came through from the other side. It was the sound of piping near the oxygen reservoir holding pressure it could not send anywhere.

Beside the door was a small inspection sheet. The last manual inspection date was 11 months ago. The signature had bled from water. After the switch to automated equipment, the manual door had apparently stopped being a passage and become a restricted zone. O Gyeongtae looked at the sheet and clicked his tongue.

"A door nobody uses is the scariest one. You don't even know it's broken."

Minchae fixed the clock under the panel and stepped back. "Can I stay here?"

Jang Yura answered at once. "Not by the door. Two steps up the stairs. Somewhere I can see you. Hands off unless I say."

"Okay. Hands off."

I stopped in front of the handle. Before my palm even touched the cold of the steel, the memory arrived first. Light. Pressure. Someone's shoulder going over backward.

"Do not open it."

Jang Yura stood beside me.

"Then another bypass."

O Gyeongtae folded the drawing. "There isn't one. If there were, I wouldn't have walked you down to this door."

Minchae's offline second hand kept moving, accurate all by itself.

The handle on the red door had not turned yet.

On the floor below, the child holding the oxygen mask coughed again. The sound was smaller than the tremor behind the door, but it made the choice faster.

I wrote in my notebook. Red door: opening suspended, conditions to be confirmed.

There was a yellow line on the floor in front of the door. Inside it was a zone for facility crews only. Right now inside that line stood a rescue team leader, a disaster analyst, a metro facilities foreman, a reporter's raw audio, and a high school student's clock. It looked like a violation of the rules, but each of us was holding something different. Yura moved people back, O Gyeongtae watched the door and the wrench, Minchae watched the clock. I was holding onto a memory. The hand doing the holding was the least steady.

The ICU patient number was called again over the radio. Oxygen saturation 87. Prepare manual bag. The lower the numbers went, the larger the red door looked. The explosion in memory and the breathing in the present hung on the same door.

"We don't open it without confirming the conditions," I said.

Jang Yura picked it up at once. "And if we still can't open it after you confirm them, then you say the reason we can't again."

She did not deny my memory. She simply refused to hand me sole command. That difference was what the door needed.

I lowered a flashlight into the gap under the red door. The water was not flowing from inside to outside. I could not feel any air movement either. If it were a pressure leak just before an explosion, there should have been some trace. The absence of one did not mean safety. It did mean there was grounds to say the scene in my memory and the scene in front of me were not entirely the same.

"Current observation," Jang Yura said.

"Pressure differential present. No leak. Door color matches. Explosion conditions unconfirmed."

"Say it that way. Not 'don't open it.'"

I nodded. The door was still closed, but the language in front of it had shifted a little.