The safe corridor was too convenient.
It began just beyond the pump junction, skirted the flooded hall and led towards the Soot up a dry incline. There were no white seals on the walls, no salt gleaming in the water, and the listener reached the halfway point without encountering a single guardsman.
Beran looked at the old map and said there was no such passage on it.
"The water should drain into the northern well. If it's dry here, someone changed the flow recently."
Saya crouched at the foot of the incline and ran the silver thread over the stone. A white grain rolled out of a crack, and beside it was a fresh scratch from a salt hook. The Guard had done more than prepare a trap. They had cleared a false way out, blocked the old drain and hidden threads where fleeing people were bound to catch them with their clothes.
"Rador isn't hunting individual sparks any more," Saya said. "He's striking at the path they take to return."
Dara suggested sending the water through the northern well again and flooding the corridor before the trap could spring. Beran refused. The current would wash the salt into the Soot's main reservoir. Then several thousand people would be left without drinking water even if the Guard never entered the district.
Marek did not lead the network in there. He took three direct sparks and joined them into a single-use decoy. Two forms mimicked a person's footsteps and heat; the third carried the faint rhythm of command traffic. From a distance they made the silhouette of Marek surrounded by a small, hot choir.
The decoy entered the corridor alone.
At the third bend, the walls struck with a white sound. Salt threads drew taut across the floor, and a concealed shutter diverted the water back towards the repair stove. The trap was not waiting for Marek's body. It was searching for a path to the external node.
The decoy's three forms took the blow and came apart. The water carried their cold powder away at once. The real network remained behind the bend, but one listener was already returning from reconnaissance through the lower pipe.
She emerged from the salt water almost colourless.
Irsa darted to meet her, but the listener managed to touch the red line on the wall. A steady glassy chime ran through twenty-four local branches.
The external node began repeating its last task.
The seams on the southern wall kept drawing together a crack that was already closed. The holders pressed against a bolt although no one was nearby. The listeners returned to the same dead end over and over. The node had not lost its strength, but it could no longer distinguish the present from a completed action.
At the pump junction, three carriers dragged an empty trolley towards the store because it still bore the mark of an earlier delivery. By the infirmary, a seam closed a steam valve that people had opened a minute before. Two listeners clogged a speaking tube with ash, still carrying out an old order to conceal it. The network was still helping. Only now its help undid everything the residents did to save themselves.
Irsa spoke to Marek in several voices at once:
"Cut off twenty-four."
Marek raised a hand towards the red line and stopped.
Beyond the southern wall were two families and the infirmary stove. Six seams held up a ceiling beam undermined during the night. If he severed the node, the beam would fall before the people could get out.
"How long?" he asked Beran.
The old man laid his metal palm against the wall.
"Less than a minute."
Marek ordered the direct sparks to get the people out. After the decoy's destruction, he had nine direct forms left, while the ceiling needed twelve points of support. People put boards and their own shoulders under it. Dara sent stove workers for screw props. Yuna ran a red thread from the infirmary to the side stairs.
She did not shout through the smoke. One raised ball of thread meant a clear passage, two meant a stretcher, three meant danger overhead. When the answer from beyond the wall stopped, Yuna struck the pipe five times. A direct listener recognised the rhythm, bypassed the looping node and found a side recess. Four patients had been left there, omitted from the evacuation list. A baker with a bandaged hand carried the last one out. He slipped on the stairs and broke his wrist, but did not let go of the child in his arms.
The local node went on tightening old seams and did not hear the new tasks.
The salt chime rose towards the stove casing. Above the metal spread a smell Marek could no longer sense: wet firewood, apple peel, a hot kettle. The salt had found the memory key.
Saya seized Marek by the wrist.
"If you break the link now, the memory can be restored."
"And if I wait?"
"The salt will reach the key. Then there'll be nothing left to restore."
The first injured man was carried out of the infirmary passage. A woman with a child followed him. The last three stove workers were still setting a prop beneath the central beam.
Marek waited.
The red line turned white halfway along its length.
Irsa no longer repeated the order. She pressed herself against the wall and held the link just firmly enough to keep the node from falling apart too soon. It was her choice, but Marek paid the price.
When the last stove worker crawled out from under the beam, Beran shouted, "Now!"
Marek struck the casing with his palm and destroyed the memory key himself.
Twenty-four local lines went dark. The seams froze on the metal, the holders released their grips, and the listeners settled into cold flakes. Their bodies did not come apart: Marek had managed to close the node before the salt struck fully. But without a freely given key, the forms could not accept a single task.
Dara ordered them gathered in a dry repair siding and counted them herself. Twenty-four. Not one form had gone down a pipe or continued a hidden command. Saya checked each one with the silver thread. Heat remained beneath their shells, but the forms responded neither to a local task nor to Marek's voice. For the first time, a ready reserve lay beside him that he had no right to use alone.
The ceiling settled onto the screw props. One cracked. Nine direct sparks and three workers held the beam while Beran repositioned the supports. After seven seconds he told them to ease the pressure, then take the weight again. The old braking rhythm worked underground as well.
The beam held.
The salt water reached the stove a few moments later. A white circle flared on the casing and immediately went out: the key no longer existed.
Marek knew he had lost the memory. He could list its details because he had spoken of them to Saya not long before. Wet firewood. Apple peel. An iron kettle.
But the words no longer led anywhere.
Beran cut an apple and held the peel to his face. Marek smelt ordinary fruit. There was no kitchen behind it, no winter, no Ella.
Saya saw that the apple peel stirred nothing in him.
"You said the memory would only become inaccessible."
"Before the trap, that was true."
"You knew the salt could erase it."
"I knew."
"And you decided not to tell me exactly what part of yourself you were putting at risk."
Marek wanted to answer that there had been no time. But Rador and Oven used the same excuse: first they made a decision for someone else, then blamed the haste.
"Yes," he said.
Saya went over to the motionless forms and checked each one with the silver thread. All twenty-four remained intact. Returning them to the network would require a new operator and a new memory, given freely.
"No more nodes without a shared ledger of the price," she said. "Not just for me. For everyone who agrees to become a key."
Marek agreed.
Footsteps sounded from the salt corridor. Nine direct sparks formed a line in front of the motionless forms, and the people of the Soot raised their tools.
Oven entered alone.
The captain had left his weapon at the bend. He unfastened his white breastplate and removed the oval copper plate from his throat. Beneath it ran an uneven burn shaped like the edge of a sealed door.
"I've heard that knock before," the captain said.
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