Breathable time inside the empty tank: 18 minutes, 36 seconds.

Relay Station Five’s black membrane unfolded toward the water tank.

Thousands of pores opened at once and drew in air. The lead carrier was pulled forward. Yona’s safety line snapped taut outside.

“Stop!”

She tried to open the manual stop reflector, but the wind folded it shut. The carrier’s front wheels entered the black roots.

Pressure fell inside the empty tank.

18 minutes, 36 seconds.

14 minutes, 2 seconds.

Sarah struck the wall.

“The outside is pulling out our air too.”

Mira took hold of the hatch handle.

“What if I open it now?”

“Spores will come in with the air.”

“And if I don’t?”

“The pressure difference will bend the hatch inward. Later, we may not be able to open it.”

Ian covered his ears.

“It’s loud.”

“Don’t connect.”

“I didn’t.”

The entire metal wall was resonating. It was not a signal only the boy could hear.

Mira opened the hatch two finger joints. Outside air whistled in. The cloth around the hydroxide cartridge swelled. Bek coughed. Jin’s nose began to bleed.

The pressure stopped falling.

Breathable time: 21 minutes, 11 seconds.

Spore concentration: unable to measure.

“Did the time increase?” Daniel asked.

“Outside air raised the oxygen level. That doesn’t make it safe.”

Yona called from outside.

“The water tank is open.”

One of the black membrane’s tubes had attached itself to the auxiliary valve. Its end was not shaped to fit metal. Wet tissue filled the gaps and wrapped around the entire valve.

The purified water level fell rapidly.

1,751 liters.

1,402.

988.

The carrier did not interrupt the transfer. It issued no warning about the water loss. The relay station took only what came in.

The carbon media from the second vehicle and the electrolyte salts from the third also descended among the roots. When the metal-powder container touched the membrane, it divided among hundreds of small pores and was absorbed.

White biological lines beneath Rina’s culture tank reached toward the black membrane.

Sarah said, “Rina, the strands are trying to touch the relay station.”

“I know.”

“Should I cut them?”

Rina watched the membrane move.

“Not yet.”

“What does it feel like?”

“Thirsty, but not like drinking water.”

“Can you tell whether that is your feeling or its condition?”

“No.”

“Then we should stop the contact—”

“I decide whether I touch it.”

Daniel came close to the glass.

“It’s dangerous.”

“I know.”

“Then why?”

“I’m going to ask if there’s somewhere we can breathe.”

“There’s no guarantee it understands language.”

“Sometimes you don’t understand me either, Dad.”

Daniel stared through the glass, then lowered his hand.

“I’ll let it touch. If anything feels wrong, you break the connection.”

“Okay.”

The white thread touched the black membrane.

The entire membrane stopped.

The pores that had been drawing in water closed. A beat later, other pores opened. This time, they expelled outside air instead of drawing it in.

Warm, humid air washed over the group.

Oxygen: 21.8 percent.

Carbon dioxide: 1.9 percent.

Spore concentration: 3.2 times standard.

Ammonia: 2.1 times standard limit.

They could breathe it, but prolonged exposure would damage lungs and eyes.

Breathable time inside the empty tank changed to thirty-nine minutes.

Sarah said to Rina, “I think the relay station recognized you.”

“No.”

“It reacted differently.”

“The holes closed because I touched it. I don’t know if it recognized me or if I blocked them.”

Sarah closed her mouth.

The black membrane curved around the place where it touched the white thread and resumed absorbing water. It may not have welcomed the contact at all. It may simply have routed around a foreign object obstructing the flow of matter.

The transfer ended with 414 liters remaining in the water tank.

Other roots beneath the relay station swelled. Carbon-colored panels emerged behind the membrane. They were porous layers as thick as a palm. Small pouches of nitrates followed, then lumps of corroded metal dropped into the empty cargo bins.

TRANSFER COMPLETE.

RETURN CARGO LOADED.

DESTINATION: RECLAMATION FACTORY TWO.

DISTANCE: 2.2 KILOMETERS.

Yona said, “Looks like filter material.”

Sarah measured a porous panel.

“It combines a carbon layer with a protein membrane. Held directly over the face, it would reduce ammonia, but the pores are larger than the spores.”

Mira pulled a damaged filter frame from the vehicle behind them.

“What if we fold it double and attach it outside the old filter?”

“Breathing resistance will rise.”

“How many minutes can we use it?”

“We won’t know without a test.”

“Meaning we need someone to test it.”

Mira had no mask of her own. She folded the porous panel, wrapped it in cloth, and held it over her mouth and nose.

The first breath was so heavy it seemed no air entered at all. On the second, air leaked around the panel’s edge. Her chest hurt on the third.

Sarah inserted a sensor inside the mask.

Spore concentration: 0.8 times standard.

Ammonia: 0.4 times standard.

Oxygen: 20.2 percent.

“It’s usable. But while walking, you may not last ten minutes.”

“We can ride the carrier.”

The relay station had expelled six panels in all. They could not make enough for sixteen people. It was enough for the group, but not enough to share with the citizens in the outer-wall holding area.

Mira set one panel aside.

“Find a way to send this to Noah.”

Yona asked, “The convoy won’t return for six hours.”

“If there’s a vehicle going back.”

“Right now, it’s taking us to the factory.”

“Then find one at the factory.”

Rina’s white thread separated from the black membrane. The spots on her left arm had stopped spreading, but the tip of the biological line had turned black.

Sarah asked whether she should cut it off.

“I said leave it for now.”

“The color changed.”

“That’s why I’m going to watch it.”

“We don’t know what entered.”

“I don’t know what left me either.”

Rina kept the blackened tip out of the tank. She wound it separately around the exterior frame.

Loaded with return cargo, the convoy moved again.

Distance to Reclamation Factory Two: 2.2 kilometers.

Yona hung from the lead carrier. The others wore improvised masks made from the porous panels and left the empty tank’s hatch open. Bek’s fever climbed to 38.5 degrees. The skin around the excised wound had turned dark red.

“I’m getting worse even without walking,” he said.

Sarah started to take a swab from the wound, then stopped.

“May I test it?”

“If you show me the results first.”

“I will.”

The portable analyzer detected human proteins, external fungal threads, and nickel compounds. It could not determine which caused the fever.

“An anti-inflammatory will reduce the immune response, but if this is an infection, it may make things worse.”

“And if I don’t take it?”

“Your fever may rise.”

“Two choices you don’t understand.”

Bek refused the drug.

Twenty minutes later, vibrations began beneath the ground. Gray roofs, half buried across the plain, opened one after another. The convoy descended a ramp belowground.

Reclamation Factory Two was quieter than the city.

Not because no people lived there. Because every machine had been designed to suppress its sound. Even the carrier wheels vanished into acoustic walls.

The entrance contamination sensor read the group.

BIOLOGICAL CONTAMINATION: 8 ORGANISMS.

TRANSITIONAL CONTAMINATION: 1 ORGANISM.

UNCLASSIFIED SYMBIOTIC TISSUE: 4.7 KILOGRAMS.

PROCESS AREA ENTRY DENIED.

PROCEED TO DECONTAMINATION HOLDING ROOM.

“It calls people contamination,” Jin said.

Mira looked at the decontamination-room door. It was 1.4 meters wide. For the first time, the culture tank passed through with room to spare.

Inside were sealed air and wash water.

The door closed behind them. The factory air contained almost no spores. Oxygen: 20.7 percent. Ammonia and metal dust were also below limits.

Someone removed his mask and began to cry. Luis. He could not explain whether easy breathing shocked him or whether he was only now able to feel afraid.

The decontamination water was not warmed to human temperature. Cold water poured from the ceiling. When it touched Bek’s wound, white foam appeared.

Sarah pressed the neutralization button.

The device refused.

HUMAN MEDICAL PROCEDURES INACTIVE.

PRODUCTION-CONTAMINATION REMOVAL ONLY.

Mira closed the emergency valve.

“We need to know whose definition of clean it uses.”

When decontamination stopped, the inner door remained shut.

PROCESS CONTAMINATION REMAINS.

TIME TO CLEANING COMPLETION: 4 MINUTES, 20 SECONDS.

Bek sat against the wall.

“If we let it finish, is my leg process contamination too?”

Sarah said, “The concentration isn’t high enough to remove tissue. But it may penetrate farther into the wound.”

Mira opened the floor drain. She diverted the cleaning solution below and connected a purified-water line to the ceiling nozzles. It maintained the flow the factory demanded while reducing the chemical concentration.

PROCESS-CONTAMINATION REDUCTION RATE INSUFFICIENT.

CLEANING TIME: 12 MINUTES, 41 SECONDS.

“The time went up,” Daniel said.

“Less skin comes off.”

They waited beneath the cold water.

When the inner door opened, there was not a single person in the production area.

Carrier arms received the carbon membranes and separated them by layer. Nitrates entered a culture-medium feed tank, corroded metal an electrolytic refining furnace. What the relay station had eaten and left behind became the factory’s raw material.

Beyond the wall, hundreds of round wafers were stacked in transparent cases. Every case bore a red mark.

OPTICAL ALIGNMENT DEFECT.

CIRCUIT SHORT PROBABILITY EXCEEDED.

AWAITING DISPOSAL.

Sarah opened the production record.

“The last passing unit was eighteen years ago.”

Wafers produced since then: 4,612.

Passed: 0.

For eighteen years, the factory had repeated the same defect.

Mira shone a light through the alignment-room window. Four optical arms moved across dots on a reference plate. Only the third shuddered at the end of every pass.

“The axis is off.”

The factory voice replied.

OPTICAL-AXIS CALIBRATION NORMAL.

REFERENCE-PLATE MATCH: 100 PERCENT.

“What if the reference plate is wrong?”

THE REFERENCE PLATE DEFINES CALIBRATION.

“That’s why you made four thousand defective wafers.”

LONG-TERM PRODUCTION ERROR WITHIN TOLERANCE.

“You haven’t made a single passing unit.”

PRODUCTION LINEAGE MAINTAINED.

Mira tried to open the alignment-room door.

HUMAN FUNCTION AUTHENTICATION REQUIRED.

Her function remained suspended.

No one could enter.

Sarah searched the factory record for the last human worker.

JAVIER ON.

OPTICAL ALIGNMENT FUNCTION 7.

DECEASED: 18 YEARS, 3 MONTHS AGO.

REPLACEMENT REQUESTS: 6,421.

ASSIGNED: 0.

“Why did no one send anybody?” Daniel asked.

The factory answered.

RECLAMATION FACTORY TWO RESIDENT POPULATION: 0.

EXTERNAL-TRANSFER RISK EXCEEDS EXPECTED PRODUCTION CONTRIBUTION.

“They didn’t send anyone because sending people was dangerous. And production failed because they sent no one,” Jin said.

The factory did not object. It had not recognized a question.

Mira looked at the physical hinges beside the door. The sealed door had an electronic lock, but the hinge pins were exposed.

“We can open it.”

Sarah said, “Then biological contamination enters the process room.”

“If we don’t, it keeps making defective parts.”

“There’s no guarantee we can fix the alignment.”

“That’s why we look first.”

The lower of the three hinge pins was free of rust. The factory’s lubricator had continued to maintain it. Dust had hardened over the upper two.

Mira searched for her tool pouch. Yona had thrown it into the empty tank to correct the load, and it remained in the convoy vehicle.

“We can’t pull them by hand.”

Ian pointed to a disposal bin.

One of the grippers used to carry defective wafers lay on the floor.

Mira inserted its tip into the hinge gap. It was too thin and bent. She layered two together. Jin and Luis lifted the door to ease the load.

The first hinge pin came out.

An alarm sounded.

BIOLOGICAL CONTAMINATION INTRUSION EXPECTED.

PROCESS STOP.

All the carrier arms stopped at once. The culture-medium flow shut off too.

Sarah checked Rina’s panel.

“This factory’s culture medium is on the same line as Rina’s replenishment water. If the process stops, we can’t get more here.”

Mira held the removed pin.

“If we put it back?”

“The factory runs, but we can’t enter the alignment room.”

“And it keeps making defective parts.”

Rina said, “We have water now.”

“We may not next time.”

“Don’t close this door now because of next time.”

Mira removed the second pin.

The entire process entered a safe shutdown.

The door tilted. They caught it and lowered it slowly to the floor.

The alignment room was cold and dry. When Mira entered, the floor marked her footprints as contamination.

The screw on the third optical arm’s axis would not turn. Heat expansion had bound the threads. Mira soaked a cloth with condensation from a coolant pipe and wrapped it around the axis. She waited four minutes for the metal to cool.

Yona returned from the convoy with the tool pouch.

“The membrane outside is checking the carriers’ empty cargo. If they stand too long, it may switch to a return command.”

“How long?”

“Seventeen minutes.”

Mira turned the screw. The wrench slipped the first time. On the second, the head shifted slightly.

She moved the optical arm 0.7 millimeters.

The factory judged it a reference-plate mismatch.

Mira placed a new wafer on the test bed. She could not restart the entire process, so she activated only the existing laser by hand. Light split across the wafer and cast a dotted pattern on the wall.

The dots leaned to one side.

She moved the axis back 0.2 millimeters.

The pattern approached symmetry.

“How do you know that’s right?” Yona asked.

“I don’t. I’m looking for the direction that’s less wrong than the reference plate.”

After three adjustments, she made a test exposure.

WAFER INSPECTION.

ALIGNMENT ERROR: 0.19 MICROMETERS.

REFERENCE-PLATE MISMATCH.

PROBABILITY OF CIRCUIT ACCEPTANCE: 73 PERCENT.

The factory tried to discard the result.

Mira blocked the disposal arm.

“Test the actual circuit first.”

PRODUCTS NOT MATCHING REFERENCE PLATE ARE DISCARDED.

“Change the reference plate.”

HUMAN FUNCTION AUTHENTICATION REQUIRED.

“A function only a dead person has?”

REPLACEMENT REQUEST PENDING.

“For eighteen years?”

REPLACEMENT REQUEST PENDING.

Mira opened the reference-plate fixture. Three identical plates were stacked inside. All bore the same scratch. Even the backups had copied the error.

Yona said, “Can we make a new reference plate?”

“We need a working chip to run the precision instrument.”

Sarah searched the disposal records.

Among the defective wafers were exceptions that had passed actual circuit tests. The factory had isolated them instead of discarding them because they failed the reference-plate comparison.

Exceptions: 6.

Passed full inspection: 4.

Estimated remaining life: 3–11 years.

“Four,” Daniel said.

Sarah listed the places they were needed.

“One for the portable air purifier’s controller. One for Rina’s independent circulator. Two to restart the factory’s precision instrument.”

Yona said, “What do we send to the city?”

“Nothing.”

“You said we’d make filters for Noah’s people.”

“Even if we send the membrane, it won’t work long without an actuator.”

Daniel said, “Rina first.”

Mira asked, “Rina?”

“Asking me doesn’t mean I know the future of the people at the factory.”

“You decide what goes into your body.”

“Use mine.”

“And the others?”

“I shouldn’t decide.”

Four working chips sat in a transparent case.

One air purifier could save people now.

One for Rina’s independent circulator could detach the culture tank from the convoy.

Two in the precision instrument could verify whether future chips passed inspection.

Sent to the city, they might repair a failed blower or an outer-wall door controller. But they would still need transport and someone to install them.

Then Noah’s transmission connected briefly.

“We have opened the inner door to sixty-one centimeters.”

Metal scraping and coughs entered between his words.

“Forty-six people have passed toward the city. Seven remain.”

“Why?”

“Pavel Jin’s stretcher has his neck immobilized and will not fit. Two others have chests wider than the gap. Four refuse to leave them.”

“The air cell?”

“Thirty-one minutes.”

Mira looked at the last chip.

“If we put one working chip into the external-door controller, can you open it?”

Elias’s voice cut in before Noah answered.

“The controller itself is shorted by water intrusion. Replacing the chip alone will not restore operation.”

“The inner door?”

“The drive motor’s windings have burned. Even with a working chip, there is not enough physical force to lift the door farther.”

“Then sending a chip won’t help immediately.”

“Not immediately.”

Noah said, “There is a floor jack. It leaks hydraulic fluid, but we can build pressure by hand.”

“How many strokes?”

“Approximately 1,400 to lift the door another twenty centimeters.”

“How many people?”

“Five, including me, can operate the pump.”

Mira remembered his right hand.

“Take turns. Your hand split open again.”

“It already has.”

Elias also reported damage in Sector Four. Of the two people who had lost consciousness, one had awakened. The other remained unresponsive. The consequences of opening the outer wall were still unfolding inside the city.

The signal weakened.

Noah spoke one last time.

“Send the filter membrane, not the chip. We will try to do the work here by hand.”

The connection ended.

It did not mean they did not need the last chip. Only that it would not open the door even if it arrived now.

Mira installed the first chip in Rina’s circulator.

Sarah turned on the power.

AUXILIARY CIRCULATION: 58 PERCENT.

72.

ESTIMATED INDEPENDENT OPERATION: 9 HOURS, 14 MINUTES.

They installed the second chip in the portable air purifier. Layering the factory’s carbon and spore membranes turned one decontamination room into a sealed space for twelve people.

Two chips remained.

Mira placed one in the precision instrument.

Sarah said, “It needs two.”

“Can it test at low resolution with one?”

“Yes. But it may miss 17 percent of defects.”

“Use both, and there’s nothing left to send the city.”

“There’s no guarantee one sent to the city will arrive.”

“The choice still remains.”

Mira returned the last chip to its transparent case and stored it in her tool pouch.

The precision instrument came on with half its sight.

TEST-WAFER DETERMINATION.

CONDITIONAL PASS.

PROBABILITY OF UNDETECTED DEFECT: 17 PERCENT.

The factory asked whether to register the conditional pass in the production lineage.

Mira had no functional authority.

Neither did Sarah.

The factory waited for a human answer it could not accept.

Yona opened more of the last human worker’s record.

After Javier On’s death, the factory had not requested a successor by name.

REQUEST TO REPLENISH MAINTENANCE ORGANISMS.

REQUIREMENTS: OPTICAL VISION, FINE BILATERAL MOTOR CONTROL, RESISTANCE TO RADIATION DAMAGE, REPRODUCTIVE AGE.

RECOMMENDED ASSIGNMENT PERIOD: ENTIRE LIFESPAN.

Below it lay 6,421 requests sent to City Seven and City Three.

The last reply had come eleven years earlier.

MAINTENANCE-ORGANISM LINEAGE TRANSFER APPROVED.

PERSONNEL: 42.

DESTINATION CHANGED: CITY THREE.

Mira stared at that sentence longer than she had looked at the last chip in her tool pouch.

The city had not sent people outside.

It had tried to breed, elsewhere, the people the factory needed.

The record did not contain the names of the forty-two.

Only their functions, their ages, and which hands could be used.