The nearest eastern signal changed before Mercy reached it.
Red. White. Red.
Then all three lights vanished.
Oliver leaned over the gauge, one hand braced against the cab window as Mercy climbed the narrow silver route. “It has gone dark.”
Tava stood behind him with the speaking tube pressed to her ear. The metal carried a faint ticking sound, too regular for static.
“It is still transmitting,” she said. “The signal is beneath the visible band.”
Nadia watched the fragment ahead grow out of the dark. It had once been a mountain or a city. Gravity had taken its middle, leaving a long staircase of stone terraces suspended between two larger slabs. Houses clung to the steps at impossible angles. Bridges hung from their undersides. Hundreds of small lamps burned along the landings, each one tethered by a separate cord.
At the bottom, a white beacon blinked beneath the fragment.
The source had reached it first.
Black lines spread across the broken stair, running from house to house and wrapping around the cords that held the lamps. The lines pulled toward a chamber opening below the lowest terrace. Inside it, objects turned in ordered rows: chairs, roof beams, tools, bundles of clothing. The source had begun its sorting.
“Can we stop there?” Tava asked.
Oliver studied the rail ahead. “Mercy can reach the upper landing. The lower half has no route.”
“Then we use the upper landing.”
“That will expose the people below us to the source.”
Tava looked at the stair. A child drifted past a window, secured by a rope around his waist. An old man crawled along the underside of a terrace, dragging a crate that spun in the air behind him.
“We do not have a choice that protects everyone,” she said.
Nadia placed her palm against the brass rail. Heat moved from the core beneath her ribs into the train’s frame. “We can give them a choice that belongs to them.”
Oliver’s eyes met hers in the reflection of the furnace glass. “The blank route is gone.”
“I know.”
“If we establish another boundary, Mercy may not have enough reserve to leave.”
Nadia looked at the black chamber below the stair. It was already drawing the fragment downward, one object at a time. The source had learned to wait for hesitation. It made every rescue resemble a claim.
Next
With Mercy nearly out of reserve and its coupling unlocking, Nadia must decide what to separate from the train before the source consumes the second fragment’s signal.
Mercy crossed the final span. Its wheels struck the stone with a jolt that threw Tava against the wall. Gold ran beneath the rails and spread across the landing, stopping at the first house. The ropes around the lamps tightened. A black line snapped across the track and recoiled into the chamber below.
The white beacon beneath the fragment flared.
A woman appeared on the roof of the nearest house. She wore a coat stitched from signal flags, and a copper mask covered the left side of her face. One hand held a lantern with three shutters.
“Do not extend the boundary,” she called.
Tava pushed open the rear door. “You sent the signal.”
“I sent the warning.”
“Your people are being taken.”
“They are choosing what to hold.” The woman lifted the lantern. Red light passed through its shutter, then white. “The source hears rescue as ownership. Keep Mercy on the landing and it will sort everyone below us.”
Nadia stepped onto the platform. Wind rose from the missing center of the fragment and tugged at her coat. “What is your name?”
The woman hesitated. Behind her, three lamps tore loose from their cords and spun toward the chamber.
“Vaska Renn,” she said. “Signal keeper of the Stair of Or.”
“Can the people below answer?”
“They can answer. They have been answering all night.” Vaska turned toward the houses. “The source changes their words before it carries them away.”
A voice came from a lower terrace. “I chose my sister!”
Another cried, “I chose the red door!”
A third voice dissolved into a harsh mechanical whisper.
“ABANDONED PROPERTY ACCEPTED.”
The black lines tightened.
Nadia reached toward the boundary. Gold light gathered around her fingers, ready to run down the stair. The core urged her forward with the old, familiar pressure: widen, gather, hold. She could feel how easily the people’s separate answers might become one glittering net beneath her hand.
Tava caught her wrist.
“Ask first,” she said.
Nadia lowered her hand.
“Vaska,” she called. “Do you want Mercy’s boundary to reach the lower stairs?”
Vaska stared at the black chamber. The copper mask hid half her face, but the uncovered eye remained fixed on the lamps below.
“No.”
The answer struck Nadia harder than a refusal of help would have. Vaska was asking them to leave people within reach of the source.
“Why?”
“Because the lower stairs have their own supports.” Vaska pointed to the cords. “Each lamp is held by a person who named what they would keep. If you connect them to Mercy, the source will call your boundary the owner of every answer it crosses.”
Pella came to stand beside Nadia, her hands dusted with flour from the mill stores. “Then what do you need?”
Vaska raised the shuttered lantern. “A witness for the signal. The warning must travel without carrying the people who sent it.”
Oliver stepped down from the cab. “A separate route.”
Vaska nodded. “If it remains separate, the next fragment may hear us before the source reaches it.”
Below them, a lamp burst. Its cord fell away, and the person holding it began to rise.
Harn moved to the edge of the platform. “Ask that person what they choose.”
Vaska shouted toward the lower stair. “Name yourself!”
The rising figure clung to a railing. “I am Senn. I choose the railing and my mother’s window.”
A gold point appeared beneath the railing. Another formed around the window. They remained several steps apart, joined by a thin thread of light that held Senn between them.
The source pulled harder.
Harn gripped the platform rail. “The answer is separate. Hold it separate.”
Nadia placed her palm on the train’s outer frame. She sent the core’s gold along the existing boundary, stopping where the upper landing ended. The light reached Vaska’s lantern instead of descending the stair.
The lantern shook in Vaska’s hand.
“Do you choose this connection?” Nadia asked.
Vaska looked at the people below. The source had wrapped black bands around the lowest houses. Their windows glowed with faces and frightened hands.
“I choose to send the warning,” Vaska said. “I do not choose Mercy as the keeper of this stair. I do not choose you for the people beneath it.”
The lantern opened.
Its red-white-red pattern shot across the dark, passing through Mercy’s boundary without entering it. A silver line formed beyond the fragment, narrow as a wire and bright enough to show the shape of another continent far ahead.
The source reacted at once.
The chamber below the stair widened. Black threads reached for the signal, but the lantern’s route bent away from them. Every time a thread touched it, one of the lamps below answered with its own color. Blue. Amber. Green. Violet. The signal broke into many distinct paths, each lamp retaining its own glow.
The source’s voice rolled up through the missing center.
“ONE WARNING. ONE OWNER.”
Vaska raised the lantern above her head. “A warning can belong to the one who gives it.”
The source seized the roof beneath her.
Stone cracked. Vaska fell to one knee, still holding the lantern. Nadia moved toward her, but Tava blocked the platform stairs.
“Ask her,” Tava said.
Nadia stopped.
“Vaska,” she called. “Do you want assistance from Mercy?”
Vaska’s hand slipped on the lantern handle. Below, the source pulled the roof another foot toward the chamber.
“Yes,” she said. “For my footing. Nothing else.”
Nadia extended one narrow gold path beneath Vaska’s boots. It steadied the roof directly under her, leaving the surrounding houses outside the boundary. Vaska rose and held the lantern toward the silver route.
The connection locked into place.
Across the eastern dark, the second signal answered.
It began with white light. Then red. Then a long pulse of black.
Oliver turned toward the gauge. The needle remained at the end of the blank region, trembling over empty brass. “That signal is not asking for a route.”
“What is it asking for?” Nadia said.
He listened to the rails.
“Witness,” he said. “And the source is already there.”
Behind them, the Stair of Or held together in separate lights. Senn’s railing and window remained distinct. The lower lamps continued to answer in their own colors. The source had taken houses, tools, and sections of stone, but its chamber could not make the warning into property.
Vaska looked down at Mercy’s wheels. “You cannot leave.”
Nadia looked toward the second fragment. Its black pulse traveled through the silver route, each beat growing stronger.
Oliver came to stand beside her. “We can leave this boundary behind. The route will remain with the lantern.”
“And Mercy?”
He glanced at the empty gauge. “Mercy will have to find another way to move.”
Nadia placed both hands on the rail. The core burned beneath her ribs, bright and immediate.
“Then uncouple the rear carriage,” she said. “We take only the signal route.”
Oliver’s expression tightened. “That carriage holds the remaining fuel stores.”
“It also holds everyone who has chosen to travel with us.”
Tava stepped forward. “Then we do not cut it loose.”
The black pulse crossed the silver route again. Far ahead, a whole section of the second fragment vanished into darkness.
Nadia looked at the people gathered behind her, at the lamps below, at Vaska’s raised warning. “There must be another choice.”
The train shuddered.
Somewhere beneath Mercy’s floor, an unused coupling began to unlock by itself.