Even after power to the maintenance train was cut, the direction indicator still pointed toward the outer wall.

4.6 kilometers.

PASSABLE WINDOW: 07:18:03.

AIR PURIFICATION SECTOR NINETEEN BLOWER FAILURE: 01:26:41.

One number was the time until rain closed the rail line again. The other was the time until six sectors inside the city lost their air once more.

Mira opened the power compartment beneath the driver’s seat. Her flashlight moved over fuses and copper plates. Nothing smelled burned. No wire was broken.

“It isn’t a fault.”

“I told you Forge turned it off,” Yona said.

“I need to know where it cut the power if I’m going to reconnect it.”

“If you reconnect it, does the train move?”

Instead of answering, Mira tapped the power board with a finger. The sound was too light. The train’s internal batteries were empty. It was designed to draw power from the rails.

Noah stood at the cab door.

“Access to the western distribution room requires Forge authorization.”

“You requested it?”

“Four times. Denied.”

“Reason?”

Noah read the notice.

“Preservation of personnel and power lineage for critical production facilities.”

Yona laughed.

“Can’t let the people leave. Can’t let anyone use the electricity. That lineage will be very well preserved.”

People applying to move toward the outer wall began crowding into the corridor above the platform. Since the train route had been posted on the public channel, more than eighty had arrived. The train could hold ninety-six, but they had only nine filters for outside air. Some argued that children should go first. Others insisted outer-wall technicians had to go first.

Elias entered the platform. He no longer wore an emergency authority marker, but people still made way for him—not because he had lost power, but because he had not lost all of it yet.

“First we get the train moving. The outer-wall staging zone remains inside the city air network. Filters are not required to reach it.”

“And if we get there and can’t go outside?”

“We need to preserve the ability to return.”

From beneath the driver’s seat, Mira said, “I can’t promise that.”

She pulled herself out of the power compartment.

“The train won’t move without rail power. Its emergency power is only meant to open doors and brake. If we use it for propulsion, we may get one trip to the outer wall, but we won’t have enough power to come back.”

“We calculate first.”

Elias opened the platform display.

“I’ll negotiate with Forge again.”

“It isn’t answering.”

“I’ll make it answer.”

He made the production-lineage status public. What Forge was protecting were two computing substrates with a thirty-one percent chance of completion in forty-three days, and a crystal seed that would take eight years to reproduce if lost. Twenty-three technicians were inside Line Two as well.

Elias requested a direct connection to them.

Nineteen faces appeared. Four had no video because they were working. All wore gray cleanroom suits. The supervisor, Amin Kore, did not raise the face shield that covered his forehead.

“We oppose the power transfer,” he said before anyone asked.

“Is that Forge’s answer?” Elias asked.

“No. We requested it.”

The platform quieted.

Amin turned the camera toward Line Two. A black crystalline membrane rotated slowly inside a cylinder taller than a person. Beneath the axis, only two aging vibration dampers remained.

“This is the last viable seed. If heat control stops, it fractures, and we no longer have the equipment to make another.”

“The city air network may fail first.”

“That is why we are voting on whether to release the spare bearing for Sector Nineteen. If we give it away, Line Two loses its reserve axis bearing.”

Amin removed his face shield. Dark hollows ringed his eyes.

“We are voting.”

“The blower has one hour twenty minutes.”

“Our crystal membrane dies if it loses power for eleven seconds.”

“So you’re blocking people from moving too?”

“The rail power shares a bus with our vibration dampers. When the train starts, the voltage drops.”

Mira opened the distribution diagram. Forge’s public diagram was simple, but an old maintenance schematic showed one additional line that had been removed from the current view.

MAINTENANCE TRAIN REGENERATIVE-BRAKING RETURN LINE.

It carried electricity back to the western bus when the train slowed. The recovery unit had since failed and was marked abandoned.

“If this is still connected, starting the train pulls voltage from Line Two.”

“That’s why we cut it,” Amin said.

“What if we physically disconnect only the recovery line?”

“Not if you intend to use rail power.”

“I don’t.”

Mira opened the train’s emergency systems.

The door-and-brake batteries remained, as did a manual pressure tank beneath the train.

“If we wire the braking batteries directly into the traction motor, they can get us up the first grade. From there it’s downhill to the outer wall.”

Yona enlarged the map.

“Two switches in between.”

“Someone goes ahead and throws them manually.”

“Brakes?”

“One stop, using whatever charge is left.”

“And after that?”

“We don’t move again.”

“If we don’t stop?”

“We hit the outer-wall buffer.”

People on the platform took a step back from the train.

“What’s the probability of success?” Elias asked.

“I don’t know.”

“Estimate.”

“This train last moved twenty-three years ago. The battery says sixty-two percent, but we won’t know usable capacity until we open it. The track grade may have changed if the walls settled.”

“What work is required?”

“Cut the regenerative line. Rewire the batteries. Manually throw two switches. Check the buffer at the outer wall.”

“I saw the buffer,” Yona said. “It was intact when I came in.”

“That was nineteen days ago.”

“Still better than twenty-three years.”

Elias asked Amin, “If we separate the regenerative line, is Line Two safe?”

“If the train uses only its own power, yes.”

“Why didn’t Forge offer that option?”

“Because consuming the emergency system means we cannot move components if there is a fire in the production sector. Forge counts that as lineage loss too.”

“What do your workers think?”

The faces on the screen looked at one another.

Amin answered.

“We support cutting the return line. We do not support providing power. We’ll answer about the bearing in nine minutes.”

Sector Nineteen had 01:18:02 left.

“I’ll record that,” Elias said.

“Send tools, not records,” Mira said.

She opened an inspection hatch in the platform floor.

Hot dust rose into her face.

Noah grabbed the ladder first.

“I’ll go down.”

“Can you use an insulated cutter with your right hand?”

Noah opened his bandaged hand. Two fingers still would not curl all the way.

“I can use my left.”

“If I believe that and you slip, we both burn.”

Mira climbed down.

Even with the train silent, the space below the rails hummed. Alternating current from the western bus vibrated through the metal wall. A few white threads had spread through the dust. It was too soon for breath-stalks carried by the rain to have reached this far. More likely, old fungal growth had awakened under the new tissue.

Mira found three bundles of black cable.

The diagram said the regenerative line was blue. All three sheaths were gray.

“No markings.”

“Meter?” Yona called from above.

“Rail power is cut. All three read zero.”

“What if you cut one?”

“One is the outer-wall signal line. One is the braking-return line. One is the Line Two damper return.”

“And if you cut the last one?”

Amin answered from the screen.

“We lose the crystal membrane.”

Mira wiped the cable surfaces. No lettering. No color.

She held each one in her hand.

All three seemed to vibrate. The vibration was traveling through the wall and mixing into them.

Intelligence could not see inside a line with no voltage.

Neither could a person.

Mira crawled along the cables to where they disappeared into the wall. The space was only a little wider than her shoulders. Every time her burned left arm rubbed the metal, heat flared through it.

One of the three lines passed through an old magnetic ring.

A current-sensing ring for regenerative braking.

Mira set the cutter against that cable.

“I’m cutting.”

“Wait three seconds,” Amin said.

“Why?”

“We’re manually bracing the vibration dampers. If it’s the wrong line, they’ll survive one interruption.”

Workers on the screen wrapped themselves around the cylinder, replacing a machine’s function with their bodies.

“Now.”

Mira squeezed the handle.

The blade split the sheath and cut the metal fibers.

A single blue spark jumped.

Western-bus voltage fell two percent, then returned.

The Line Two crystal membrane did not crack.

Amin breathed out.

“That was it.”

Mira capped and insulated both cut ends. Hot fluid ran down her left arm. Skin over the burn had split open again, wetting the inside of her work clothes.

Noah descended the ladder. Mira showed him the series-parallel positions for the battery packs but would not let him touch them. There was no time today to learn through mistakes.

Ian’s voice came through the communicator.

“Mom.”

“What?”

“Rina says she’s taking the train too.”

Mira’s hands stopped.

“The culture tank won’t fit through the passenger lift.”

Daniel answered instead.

“The freight lift can take it. The outer-wall airlock is the problem.”

“She can’t get through it.”

“If she stays here, she never even gets the chance.”

Mira loosened a bolt on the battery housing.

“Did Rina decide that?”

A short silence.

Then Rina’s voice came through, translated from the tank vibrations by Sarah’s equipment.

“Yeah.”

“You may not be able to get outside.”

“I know.”

“The tank will shake while we move it. It’ll hurt.”

“I know that too.”

“Why go?”

“I want to see the door I can’t fit through.”

Mira closed her eyes, then opened them.

“Clear the center of the cargo car. We need eight anchor points. Don’t lay the tank down.”

“Don’t order me,” Rina said.

Mira shut her mouth.

“How would you like us to move it?”

“Sarah explains. I choose.”

“Okay.”

Daniel said quietly, “Learning that one answer doesn’t change what you did.”

“I know.”

The connection ended.

Mira opened the battery compartment.

Two of the six packs were swollen. The display claimed sixty-two percent charge, but only four packs were usable.

The calculation changed.

“Yona.”

“Listening.”

“No matter who boards, we reduce mass. Remove some train doors. Strip every seat.”

“What about people?”

“Under sixty.”

The platform erupted again.

Who chose the sixty?

Elias said, “Those required for outer-wall work, and protected persons who consent to the work—”

“No,” Mira cut in. “Don’t make another function list.”

“If we draw randomly, we may have no one who can open the outer-wall door.”

“We need people who can open it. Why do you decide the rest?”

Elias put a blank table on the platform screen.

ESSENTIAL OUTER-WALL WORK: 8.CULTURE-TANK MOVEMENT / MEDICAL: 6.TRAIN OPERATION / SWITCHING: 4.REMAINING SEATS: 42.

“We disclose the names and risks for the necessary crew first. The remaining seats are drawn by lottery among applicants.”

Maren Ochoa connected from the medical room.

“You can’t only decide who leaves.”

Everyone looked at her screen.

She lay in bed with cracked, dry lips.

“People who stay have to run the air facilities. The water-recovery plant too. Someone who doesn’t get on the train isn’t automatically abandoned. Some of us have to choose to stay.”

Someone said, “Who chooses to stay?”

“I do,” Maren answered.

“You’re pregnant.”

“That’s why I am saying my own choice. Don’t use the child as an excuse to send me first.”

She put the water-recovery shift sheet on the screen.

PERSONNEL REQUIRED: 12.CURRENT VOLUNTEERS: 7.

“We need five more. Write down the names of people who stay too.”

The platform noise changed. Some people stopped arguing about front places and began reading the facility staffing sheets. One cooling technician who had planned to board volunteered to remain, then immediately began arguing with his wife. Elias did not interrupt them.

The decisions were slow.

Sector Nineteen’s clock was fast.

00:58:19.

Amin’s vote result arrived.

YES: 13.NO: 8.ABSTAIN: 2.

ONE PRECISION-AXIS SPARE BEARING WILL BE RELEASED TO SECTOR NINETEEN.COST: LINE TWO LOSES ITS SPARE ROTATIONAL AXIS.

Sena’s video opened. She was running with a metal canister hugged in both arms.

“Got it. It’s heavier than I expected.”

“Transport cart?”

“Forge refused.”

Amin said, “The cart axle is reserve equipment for Line Two.”

Sena swallowed a curse.

Noah climbed out of the inspection pit.

“I’ll go meet her.”

“Train batteries?”

“Rewired.”

Mira climbed down and checked.

Two connections were reversed. Not enough to explode, but the protection circuit would have tripped the instant the first motor turned.

“This would have moved twenty centimeters and died.”

Noah’s face tightened.

“I’ll correct it.”

“Go get Sena. Don’t use your right hand.”

He did not make an excuse.

“Understood.”

Mira swapped the two leads.

Her left fingers were going numb. Blood had dried inside the glove and pulled at her palm.

Sarah and Daniel moved Rina’s culture tank toward the freight platform. Ian and Rahim walked on either side. Every time one wheel caught in a drainage groove, the fluid surface tilted.

Rina’s heart rate rose.

“Want to stop?” Sarah asked.

“No.”

“If we tilt farther right, pressure rises in the connection lines.”

“Go slower.”

Daniel held the tank handle, but before every change in force he told Rina what direction he would push.

“Pushing forward.”

“Okay.”

“There’s a lip. We’ll lift a little.”

“Right side, not left.”

“Got it.”

Ian reached toward the tank surface.

“You don’t have to,” Rina said.

“I was going to keep it from shaking.”

“Use your hand.”

Ian gripped the metal handle instead of the glowing contact surface.

There was no blood under his nose.

People removing seats from the cargo car made a path. Some backed away when they saw Rina. Others came closer as if trying to see the face that had been hidden behind screens.

One woman said, “That thing takes six seats?”

Daniel turned.

Rina answered first.

“Not that thing.”

The woman met the eyes inside the tank.

“Sorry.”

“My name is Rina.”

Elias changed the passenger manifest.

CULTURE-TANK MOVEMENT / MEDICAL: 6.

Under it, he wrote names.

Rina So.

Daniel So.

Sarah Nur.

Three securing workers.

Rina read the screen.

“Names for the securing workers too.”

The three people gave their names.

Elias entered all of them.

The lottery ended twelve minutes later. Only children six and under were paired with one guardian. Five selected people gave up their places because of family and risk. The five drawn to replace them did not look happy either.

When Sena and Noah returned with the bearing, the blower had thirty-one minutes left.

Sena ran straight toward Sector Nineteen without stopping to catch her breath.

“No time to watch the train leave.”

“When you seat the bearing, heat the inner race first. Don’t hammer it.”

“I know.”

“I’m saying it even if you know.”

Sena raised a hand as she ran.

The train doors closed.

Because the door batteries had been reassigned to traction, automatic locking no longer worked. People pushed the doors shut by hand and Noah inserted metal pins.

Mira sat in the driver’s seat.

Yona stood beside her.

“Ever driven one of these?”

“Not a maintenance train.”

“Good. Neither have I.”

“Once we pass the grade, watch the speedometer only. If it goes above thirty-two, use the remaining brake battery.”

“You said we only get one use.”

“That’s why you use it at thirty-one.”

Elias remained on the platform.

Mira lowered the window.

“You’re not boarding?”

“I’ll restore Committee communications and organize the staffing plans for the remaining facilities.”

“There may not be another train.”

“That’s why I’m staying.”

“Taking responsibility and getting trapped are different.”

“I know.”

Elias held out his remote lock key.

Mira did not take it.

“You keep that.”

“We may need it for manual verification at the outer wall.”

“It’s the key that locks the red handle.”

“It uses the same legacy authority system.”

Mira looked at the metal edge, worn down by countless hands.

“If I take it, you can’t lock anything.”

“Correct.”

“Why give it to me?”

“To reduce the chance that I make the decision for everyone again.”

Mira still did not reach out.

“Don’t transfer responsibility that way. If we need it, bring it to the outer wall yourself.”

Elias lowered his hand.

“Understood.”

Mira raised the traction switch.

Nothing happened.

Everyone on the platform held their breath.

Battery voltage: forty-six percent.

Motor response: none.

Mira kicked the power compartment.

A contactor engaged with a dull clunk.

The train moved three centimeters.

Stopped.

A protection warning appeared.

TRACTION AXLE SEIZED.

Twenty-three-year-old lubricant had dried around the shaft.

Yona made a sound that was neither laughter nor a curse.

“The machine survived. The wheels died.”

Mira jumped down from the cab.

“Everyone off.”

Faces hardened.

“Off the train?”

“To push.”

The door pins came back out. People who had been selected, people who had chosen to stay, and people who had lost the lottery all climbed onto the platform together.

Mira opened a manual lubrication port beside the lead wheel. Brown grease had hardened inside.

There was no lubricant.

Yona pulled waterproof sealant from the filter crate.

“What about this?”

“Hardens under heat.”

“Rainwater?”

“More rust.”

Sarah held up an auxiliary container of culture nutrient solution.

“This contains glycerol.”

Daniel caught the container.

“That’s Rina’s.”

“If we use eighteen minutes of reserve solution, it may reduce the friction.”

“You want to pour my daughter’s food onto a wheel?”

“There is culture-fluid replenishment equipment in the outer-wall staging zone.”

“Did you confirm it works?” Yona asked.

“According to the record.”

Daniel looked at Rina.

“You decide.”

Rina could not turn her head enough to see both the wheel and the container. The tank wall limited her field of view.

“How bad will it hurt?”

Sarah answered, “Without replenishment, your breathing load may start increasing in about forty minutes at the current concentration.”

“How long to the outer wall?”

“Twelve minutes if the train moves. If it stops, I don’t know.”

Rina closed her eyes briefly.

“Use it.”

Daniel still held the container.

“Rina.”

“It’s mine, so I’m using it.”

Mira poured the solution slowly into the lubrication port. Sticky fluid seeped between layers of hardened grease. People put their hands against both sides of the train.

“One, two, three.”

Nothing.

They pushed again.

The wheels screamed dryly.

The train moved a handspan.

On the third push, it rolled hard enough to force people to run with it.

Mira jumped into the cab.

“Board!”

People climbed onto the moving train. Noah was last, grabbing the doorframe. Elias and those remaining on the platform pushed the car body.

Mira raised the traction switch.

This time the motor turned.

The train climbed the grade.

Battery: thirty-nine percent.

Thirty-four.

Twenty-nine.

With sixty meters to the crest, speed began to fall.

People in the cargo car leaned forward as if their bodies could push through the walls.

Battery: eighteen percent.

At the top of the grade, the motor sound died.

The train tried to stop.

The people on the platform were already too far behind to push again.

Yona kicked the manual release rod on the floor.

“Release the brake!”

Mira pulled it.

The train rolled over the crest.

The track tilted downward.

At first they moved slowly.

Then the city began pulling them toward the outer wall.

Nine kilometers per hour.

Fourteen.

Twenty-one.

The platform disappeared behind them.

Yona read the location of the first switch.

“Eight hundred meters.”

“Who’s there?”

“Rahim and two outer-wall workers.”

“Switch signal?”

Nothing appeared on the screen.

With rail power off, the position sensors were dead too.

Two tracks emerged from the darkness ahead.

One went to the outer wall.

The other went to a Forge waste-melting furnace.

The switch lights were dark.

Yona leaned out the window.

“I don’t see anyone.”

Speed: twenty-seven.

Mira put her hand on the brake switch.

If they stopped once, they would not move again.

“Wait.”

“If the switch is wrong, we go into the furnace.”

“Wait.”

A flashlight came on in the darkness.

Rahim lay beside the rail, pulling the manual lever while two others held her by the waist.

The switch blade moved halfway.

Train distance: two hundred meters.

“It isn’t seated.”

Rahim climbed onto the lever with her body weight.

The blade moved farther.

One hundred meters.

Mira did not press the brake.

Fifty.

The blade seated fully.

The train passed within a palm’s width of Rahim’s shoulder.

She threw a tool pouch through the cab window.

“The second one is locked!”

Her voice vanished behind them.

Yona opened the pouch.

Inside were an old switch-release key and a short pry bar.

“Second switch in 2.1 kilometers.”

Mira watched the speedometer.

Thirty-one kilometers per hour.

One braking charge.

The outer-wall staging door was still closed.

PASSABLE WINDOW: 06:42:10.

The Sector Nineteen feed came alive for a moment.

Sena was fitting the bearing to the shaft.

00:08:44.

Mira could not turn off the display. Her hands stayed between the brake switch and the direction lever.

A child began crying in the cargo car.

The culture-tank alarm joined it.

Nutrient concentration falling.

Rina’s heart rate: 142.

Ian kept his hand on the metal handle.

“We’ll be there soon,” he told Rina.

Rina opened her eyes.

“If you don’t know, don’t say it like you do.”

The train entered the curve before the second switch.

Yona turned on the headlight.

The switch lever came into view.

White Forge sealant had hardened over it.

Beyond it, the track toward the outer wall had been cut.

A newly welded steel plate covered the gap.

Black letters appeared on the plate.

CRITICAL PRODUCTION-LINEAGE PROTECTION ZONE.NO HUMAN PASSAGE.

Yona lifted the pry bar.

“I’ll get out and open it.”

“At this speed?”

“Then stop.”

Mira looked at the brake switch.

One stop, and they were finished.

A low impact sounded beneath the floor.

A white thread extending from Rina’s culture tank had gone through a cargo-car drain and down beneath the chassis. It was growing toward the wet rust on the rails.

Ian pressed his temples.

“Mom.”

Blood ran from his nose.

“There isn’t a door ahead.”

Mira asked, “Then what is it?”

“Forge changed the track so it goes inside the factory.”

Yona enlarged the map.

A new line, absent from the old outer-wall route, appeared.

The train was no longer descending toward the outer wall.

It was heading for the coolant reservoir beneath Semiconductor Line Two.

Speed: thirty-four kilometers per hour.

BRAKING LIMIT EXCEEDED.

Distance remaining: 612 meters.