They had to choose who went north before the chip was complete.

City Three water: 11 hours, 38 minutes.

Travel to the northern junction: 11 hours, 32 minutes.

Margin: 6 minutes.

“At T-12’s speed,” Mira said.

With one bent front wheel, the carrier could not exceed four kilometers per hour. Six minutes remained only if the ground stayed level, nothing else failed, and the map omitted no obstacles.

Nami requested another carrier from the Corridor.

NO CARRIER AVAILABLE FOR LOAN.

T-12 RECOVERY OR FIELD DISASSEMBLY RECOMMENDED.

“If we repair it ourselves?”

REQUIRED WORK TIME: 5 HOURS, 40 MINUTES.

CITY THREE REPAIR PRIORITY SUSPENDED.

The Corridor did not alter yesterday’s agreement.

Mira fixed a temporary brace over T-12’s bent axle. It did not increase speed, but reduced the chance the wheel would detach.

“I’ll go with Ian and Yona.”

Yona looked up. Her lip color had recovered after the hypoxia, but standing long shortened her breath.

Sarah objected.

“Lung-function test first.”

“We need someone who knows the northern facility.”

Nami said, “I’ll go. I know City Three’s old waterway.”

“You have to make the pump decisions.”

“The conditions are already approved. Jin and Mateo can implement them.”

Mira left Yona behind.

“Find City Six’s pipe records. Before we touch a valve, we need to know what sectors it connects.”

Yona did not object. Before, she would have followed as if proving her body.

“Communicate while alive,” she said.

“I can’t if I’m dead.”

The advance team was Mira, Nami, and Ian. They loaded six liters of water, two relay-station filter membranes, a manual cutter, and four pressure plugs. Nothing for the return. With the bent axle, T-12 could carry only forty-one kilograms.

Daniel did not leave the medical wing.

Just before departure, Sarah examined Ian’s fingers. The ring and little fingers of his right hand closed 0.4 seconds behind the command from his palm.

“Slower than yesterday.”

“They still work.”

“Whether they work and whether they are being damaged are different questions.”

Sarah attached a conduction patch. Low frequencies moved the muscles normally, but the neural return signal overlapped twice.

Estimated reversible interval: 9–13 days.

Median: 10 days, 19 hours.

He would not die afterward. It was the point at which permanent finger delay and sensory confusion became more likely than not.

“Does it extend if I don’t connect?” Ian asked.

“We haven’t isolated the cause. Forge low frequencies, biological-network contact, and Archive overload overlap. Not using it may slow the damage.”

“May.”

“Anything stronger would be a lie.”

Sarah waited long enough for refusal before storing the result. She shared only the numbers with Mira, not the raw neural data.

Ian climbed onto T-12.

“We just have to fix it within ten days?”

“Within ten days, we need to discover what to fix,” Mira said.

Another clock.

T-12 headed north.

At City Three, the factory test process continued.

Jin read remote values line by line.

Alignment error: 0.21 micrometers.

Insulation contamination: 0.7 percent.

Expected high-temperature logic inversions: 3.2 per 10,000 cycles.

Within the conditional range for pump control. But the wafer edge cracked during final cutting.

Only one test chip would emerge, not two.

Water remaining: 8 hours, 17 minutes.

Process completion: 4 hours, 29 minutes.

Cargo transfer: 3 hours, 31 minutes.

Margin: 17 minutes.

One delay and the chip arrived at a dry city.

Asha measured the black biological line in Rina’s tank. It had stopped after reaching toward the drain, but seven small nodes had formed near its root.

“This test is not asking you to reverse your refusal,” Asha said first.

Rina made the membrane transparent.

“If the test needs that statement first, it’s dangerous.”

“I think it’s better than not knowing the danger.”

Daniel sat across the room with his screen off.

Rina permitted the test.

The tissue nodes were not new respiratory membranes. They resembled storage organs that concentrated nutrients from the culture fluid. At the present rate, they would surround the circulation intake within eleven days.

Window to intervention: 8–14 days.

Median: 11 days, 3 hours.

No one knew what happened afterward. The growth might stabilize culture-fluid flow or block circulation.

“The same clock as Ian,” Daniel said for the first time.

Sarah shook her head.

“Similar numbers only. Ian’s is neural conduction. Rina’s is external-tissue growth. We cannot join them as one cause.”

“Both eleven days by coincidence?”

“Overlapping ranges do not connect clocks.”

Rina asked, “Cut only the nodes?”

“Vessel-like tubes connect through the entire line. We can’t predict bleeding or circulation shock after cutting.”

“Then what must I do in eleven days?”

“Choose whether to observe, test growth suppression, or let your body use them.”

“I choose all of it?”

“Yes.”

Rina looked at Daniel.

“You heard?”

Daniel nodded.

“I heard.”

“Don’t press anything for me.”

“I won’t.”

Not reconciliation. One promise that could be checked.

Rain began nineteen kilometers north.

At first, a few heavy drops. Soon water filled T-12’s wheel tracks. Outside moss raised its leaves and released black spores across the rain.

Mira and Nami layered another relay-station membrane over their faces. Ian used the portable detector without connecting his senses.

SPORE CONCENTRATION EXCEEDS CERTIFIED RANGE.

“Detour?”

T-12 retrieved three roads from K-41’s terrain memory. The first led to yesterday’s collapsed channel. The second had closed in a landslide twenty-four years ago. The third added 8.6 kilometers.

The present terrain matched none.

Nami watched the rain flow.

“Follow the top of the old waterway embankment.”

“If it floods?”

“Later than below.”

T-12 climbed. Whenever the bent wheel sank, Mira and Nami pushed. Ian probed the ground ahead.

Speed fell to 2.7 kilometers per hour.

Estimated arrival: 16 hours, 4 minutes.

More than four hours after City Three’s water ended.

“Too late if we turn back,” Ian said.

“Too late if we continue,” Nami answered.

Mira enlarged the northern intake map. An old inlet pipe met the embankment seven kilometers ahead. If open, they could abandon T-12 and walk inside.

“We leave the carrier.”

The Corridor displayed the cost.

T-12 field abandonment: 68 percent flood-damage risk.

Expected recovery: 12–21 days.

Ian asked, “Does it request disassembly?”

T-12 answered directly.

CURRENT WORK CONTINUES.

The carrier still had a purpose.

They moved slowly to the inlet pipe. The cover was half open. Cold air flowed out.

Mira unloaded only the cutter and pressure plugs. They took three bottles of water.

“Wait here.”

T-12 did not answer. They could not tell whether its work purpose was transporting people or reaching the junction.

Ian rested a hand on the chassis.

“What if we don’t return?”

WAIT: 21 DAYS.

The upper limit of the Corridor’s expected recovery time.

The three entered the pipe.

The factory cut the test chip nine minutes late.

Final inspection appeared on City Three’s wall.

Low-speed control: pass.

High-speed control: conditional fail.

Expected degradation: 73–410 hours.

A passing component that could fail at any time.

Jin placed the chip in a cargo capsule. Tube pressure was 71 percent, lower than when they sent the filter membrane.

“Estimated arrival?”

6 hours, 58 minutes.

City Three water: 7 hours, 11 minutes.

Margin: 13 minutes.

As the capsule launched, the pressure controller shuddered. A working chip had restored it, but fragments of relay-station membrane clung inside the pipe.

Pressure: 63 percent.

Estimated arrival: 7 hours, 46 minutes.

Thirty-five minutes after the water ended.

Jin tried to activate the next compressor remotely. Forge refused on safety limits.

“Manual approval?”

HUMAN ON-SITE CONFIRMATION REQUIRED.

The compressor was in a basement 1.8 kilometers from the factory.

Bek stood. Temperature 38.2 degrees. The spots had stopped spreading.

Sarah said over the comm, “Going outside exposes you again.”

“I know.”

“You said you’d take the advice this time.”

“That time, the work didn’t need me.”

“Someone else can go now.”

Luis limped on his left ankle. Jin could not leave the process room. Yona was recovering from hypoxia.

Bek asked, “Who?”

Sarah could name no one.

Bek took an external membrane and filter to the compressor. He did not run. He alternated walking and rest to keep his heart below 150.

The capsule moved through the pipe ahead of a weak pressure wave.

City Three water: 5 hours, 2 minutes.

Capsule arrival: 5 hours, 31 minutes.

Black water filled the compressor-room entrance when Bek arrived. At knee depth, his shin wound would be submerged.

He sent Sarah the image.

“Chance of infection if I enter?”

“I can’t calculate it.”

“If I don’t?”

“City Three residents with external respiratory membranes are at risk first.”

Bek took out the anti-inflammatory he had refused the day before.

“If I inject this now?”

“It reduces the immune response, but may worsen an infection.”

“I choose.”

He put the drug back without using it. He wrapped three layers of resin membrane over the wound and entered the water.

The manual compressor lever was submerged.

Bek raised it with both hands.

Pipe pressure rose to 82 percent.

Estimated capsule arrival: 4 hours, 11 minutes.

City Three water: 4 hours, 32 minutes.

Margin: 21 minutes.

When Bek left the water, one black dot had appeared inside the resin.

He showed Sarah instead of hiding it.

The northern inlet pipe flooded after five kilometers.

Mira stepped in first. Water reached her knees, waist, chest. It was cold and smelled of nickel.

Nami asked, “Turn back?”

“Detouring outside puts us behind the water clock.”

“A blockage inside and none of us returns.”

Ian struck the wall. The echo returned short from fourteen meters ahead.

“Not fully blocked. There’s air above.”

“Did you connect?”

“I listened with my ears.”

He struck again. Mira heard it too. Water moved between the echoes.

They walked with equipment above their heads. Where water reached their chins, Nami’s foot fell into a floor opening. Mira seized her arm. Ian anchored himself to a wall cable and pulled them both.

Water rushed into the hole.

“The intake-tower drain still works,” Nami said.

Moving water meant the northern facility was not wholly dead.

They reached the junction as the chip capsule crossed its final pipe segment.

The northern facility was not a tower.

It was half of what had been a tower.

A gray mass had struck at an angle from the sky, tearing through the intake tower and nitrogen-distribution building together. Wreckage from the orbital transmitter. Rainwater filled the crater. A severed nitrogen pipe released small bubbles underwater.

Nitrogen leaking for eighteen years accounted for part of the 393 tons missing from the records.

Groundwater still rose beneath the intake tower, but wreckage insulation and rust blocked the inlet. Overflow drained away as waste.

There was water.

It simply could not reach City Three.

Nami measured flow.

690 liters per hour.

Mira asked, “Open the central pipe and it reaches the city?”

“We don’t know the damage between. Not all of it.”

Even nine percent arriving would exceed the present pump-cooling loss. But disturbing the nitrogen pipe while clearing the intake could release the remaining gas at once.

Two infrastructures lay beneath one wreck.

The capsule arrived at City Three.

Jin and R-8 removed the old controller and connected the test chip.

Water remaining: 18 minutes.

The chip issued its first startup signal.

Pump output: 43 percent.

47.

52.

It stopped at 57, before the conditional high-speed range.

Inflow: 241 liters per hour.

Expected coil reshort probability: 29 percent.

Water-membrane survival: 26 hours.

The city gained a day.

Chip degradation revised to 61–208 hours. It could not be returned to City Seven.

The return condition had not been met.

Noah answered briefly.

“Record it. Those were the conditions we approved.”

The air network’s fourteen months would shrink without the chip.

In the north, Mira entered the wreckage. Most of the orbital object’s shell had burned and torn, but the central recorder rested atop the nitrogen pipe.

Moving it caused a leak.

Leaving it blocked more than half the intake.

Nami said, “Cut away the recorder and open the water first.”

Ian asked, “What’s inside?”

“Something we lived without for eighteen years.”

“The nitrogen?”

“We can plug the pipe. If two of four plugs fit.”

“If they don’t?”

“The city-network air clock shortens.”

Mira raised the cutter. Opening water saved today. Preserving nitrogen saved months. Recovering the recorder whole might hold something machines needed in twenty-three years.

No space to preserve all three.

“Secure the recorder first,” Mira said.

Nami turned.

“Delay the water?”

“No. Tie it so it doesn’t tear the pipe when we open the water. We read it later.”

They wrapped severed cable around the wreckage. Ian entered the gap to set a knot while Mira pulled from outside. He did not use his connected sense. Nami prepared pressure plugs on both sides of the nitrogen pipe.

Mira cut the insulation blocking the intake.

Water poured through the first opening. The recorder shifted and pressed the nitrogen pipe.

Nami inserted the first plug. Six millimeters too small. Gas leaked between her fingers.

The second was too large.

Mira wrapped cut insulation around it. Nami hammered it in.

Leak reduced 81 percent.

Not sealed.

Intake flow opened to 511 liters per hour.

Estimated arrival at City Three after line losses: 74–203 liters per hour.

The city’s one day might become two and a half to four. Six more pipe failures required repair.

Nitrogen storage recalculated from 318 to 287 tons.

Air-network median: 12 months, 26 days.

One repair had cut almost two months from fourteen.

City Three did not know. The junction’s remote sensors failed the day the wreck fell. Rain and terrain blocked the portable comm from the Corridor relay.

Nami said, “We sent the water. We wait for it to arrive.”

“The city may think we failed and raise pump output.”

Mira remembered the chip’s conditional high-speed failure. Raising output without knowing about northern inflow could create a pressure collision and rupture the water membrane.

Water would arrive in at least one hour, forty-six minutes and at most four hours, twenty minutes. They had to warn the city first.

Ian looked at the recorder’s indicator.

“That machine transmitted to orbit.”

“Eighteen years ago.”

“T-12’s memory was old too.”

Old did not mean dead. It meant the present had to be checked.

Mira opened the recorder shell. The transmitter had burned in the collision. Only the receiver and short-range landing-guidance antenna remained. Its output could not reach the Corridor, but the surface steel frame of the nitrogen building might amplify it.

The frame lay across the intake. Moving it required reducing flow again.

“We don’t close the water,” Nami said.

“Then we connect without closing it.”

Mira unwound thirty meters of severed guidance wire. She had to cross the current to the frame. The water struck her knees as soon as she tied the cable around her waist and entered.

Ian held the cable behind her.

“If you lose it, it drags me too.”

“Then don’t lose it.”

Nami remained beside the intake valve, ready to reduce flow if pressure rose.

On Mira’s second step, floating insulation struck her shin. Her third slipped. The cable tightened around her waist and pulled Ian forward.

He wrapped his whole arm around the line instead of using his fingers. He did not rely on the two that closed late.

Mira raised one knee underwater and stood. At the frame, she wound the guidance wire around a rusted bolt, scraped the metal clean for conduction, and pressed the line against it.

The recorder sent a nineteen-second signal.

INTAKE OPEN.

EXPECTED ARRIVAL FLOW: 74–203 LITERS.

DO NOT RAISE PUMP OUTPUT ABOVE 57 PERCENT.

NITROGEN REMAINING: 287 TONS.

No answer.

The second transmission halved the recorder voltage. There would be no third.

Four minutes later, the Corridor’s acknowledgment vibrated through the frame.

RECEIVED.

At City Three, Jin canceled the pump increase. The test chip continued at 57 percent.

Northern water arrived two hours, thirty-one minutes later.

Initial flow: 81 liters per hour. Mixed with rust and insulation fiber, it could not enter the water membrane directly. City Three emptied one food culture tank and converted it into a settling reservoir. Two had already gone dry. A third source of food stopped.

Actual filtered inflow: 63 liters per hour.

Water-membrane survival: 2 days, 18 hours.

Repairing the six northern failures could extend it to 4 days, 7 hours. The repair team had no sacrificial electrodes left.

The city gained water and lost food and its next repair material.

Rina watched the values through the transparent membrane. The 310 liters she released were already sustaining fifty-two external respiratory membranes. They could not return, and had no reason to.

Daniel said, “More came in than the water you gave up.”

“It didn’t come because I gave it up.”

“I know.”

He did not call the water compensation produced by his daughter’s sacrifice.

“Mira sent it from the north.”

Rina looked briefly at the nodes on her black line.

“Ian?”

“With her. No injury report.”

“Only tell me that.”

Daniel added no medical values and no choices.

At the junction, the three could not prepare to return. Rain intensified, filling the inlet pipe where T-12 waited. The cable securing the recorder was temporary. The nitrogen plugs lost pressure every hour.

Nami wrote a repair list.

Central-pipe breaks: 6.

Permanent nitrogen plugs: 2.

Replace intake filter layer.

Recover orbital wreckage.

Minimum personnel: 14.

Estimated time: 6 days.

City Three’s Corridor repair priority was suspended for fourteen days. Human hands and remaining city parts would have to do it.

Ian asked, “We have ten days. If repairs take six?”

“Four remain,” Mira said.

“And travel back.”

“Then three.”

“What can we do in three?”

Mira could not answer. City Three had neither a way to repair Ian’s nerves nor equipment to learn what Rina’s line was building.

The recorder came on again.

The Corridor’s twenty-three years had not changed.

Ian’s hand: 10 days, 14 hours.

Rina’s biological line: 10 days, 22 hours.

These numbers were not time left to live.

They were time left to postpone the next choice.

The recorder hung on a cable, half above the water. A small indicator lit behind a crack in its shell.

It had not been dead for eighteen years.

The submerged photovoltaic panel had emerged and restored power.

The screen showed no rescue request.

LANDING-CARGO TRANSFER LIST.

BIOLOGICAL ADAPTATION REFERENCE SAMPLES: 27.

GROUND TRANSFER COMPLETE: 24.

UNTRANSFERRED: 3.

Three coordinates appeared.

One lay 1,840 kilometers north, where Nur’s signal originated.

One lay beneath City Seven.

The last was moving.