Derva had the stair-hoist brake in pieces when someone knocked.
The people in her building struck the door with whatever part of themselves was free: a shoulder under a basket, a boot when both hands held a child, three fingernails when they wanted the key to the roof. This sound landed exactly where bare knuckles would, one measured blow, a pause, then another.
The little brass washers on Derva's floor jumped before the third.
Far below, a facade the engine had clipped on its last run finally gave way, and the apartment leaned with it. Lime dust breathed from the crack above her sink. The hoist cable inside the open brake housing twanged against her thumb.
Six minutes and some change since the last impact. The backward thunder would come at seven.
Derva set the brake shoe down and opened her door.
The god of death knelt on the landing.
She knew him without robes, scythe, or skull. He wore the shape of a tall man in travel-gray, but the unlit space inside his outline had the depth of a night sky. Worship moved through that depth like faraway lanterns. His lowered knee had not dented the stair runner. Dust lay undisturbed beneath his other boot.
"Derva," he said. The landing gave his voice a small, awkward echo. "Please choose me."
She kept one hand on the door. "You have the wrong flat."
"Any willing adult inside the ward would suffice. Yours was the last open door between here and the charge."
"Choose you for what?"
His head came up. There was a face in the darkness now, spare and solemn, trying to hold a ceremonial expression together under plain fear.
"As your earthly avatar," he said, "and your champion."
The district bell began hammering below: five strokes, the signal for the eastern evacuation lane. People shouted in the stairwell.
Derva looked past him. Through the landing window she could see the demonstration engine at the foot of the slope, or what remained of it: a plated prow buried in the old test barricade, six wheels crooked along the paving, the brass memory drum in its belly pulsing red. It had been built to remember one charge supplied by forty living spellwrights. Nobody drove it, and it wanted nothing. Its stop-pin had snapped on the first run.
As she watched, red light ran backward over the wreck. Torn plates shuddered. Beams ripped from a cooper's roof and flew toward the engine. Iron guttering peeled from three facades, twisting into wheel rims. The prow drew itself out of the barricade and vanished uphill in a clap that hurt her teeth.
The next circuit had begun.
"My champion," Derva said. "You're asking to work for me."
"Yes. The rite usually runs—" He stopped and started again. "I cannot take a body inside this ward ring without a living patron. The people who pray to me are not inside it. Give me a cause, and I will serve it."
Up the street, metal began to turn.
Derva knew that sound. The engine was back in the arsenal yard, its remembered wheels gathering speed. On its first circuit it had shattered the test barricade. The roadway had settled under that weight; when the engine came again, the old grooves would tip it east toward the lower bridge. The reservoir sluicehouse stood beyond the next bend. If the prow entered the gate gallery, it would break the manual gearing or the wall around it. Either failure would put half the reservoir through the lower district.
"What can you do?" she asked.
"End what has already finished ending. A spent spell. A break that has gone all the way through."
"The engine resets every seven minutes. End that."
"Its charge has not ended. The broken pin took away the end it was given." He was quiet a moment, and when he went on the measure had gone out of his voice. "I have heard it all morning. It starts, and runs, and starts again, and I cannot— I want it finished. Please."
Derva looked back at her floor: the brake shoe, the washers, the coiled hoist cable. It was the best kit in the building, and none of it could touch the engine.
She stepped onto the landing. "I choose the god of death as my earthly avatar and champion for one cause: end this repeating charge without surrendering the lower district to it."
"Freely?"
"Yes."
For the first time, his boot pressed dust into the runner.
His shadow leaped beneath hers. Cold folded around Derva's ankle and fitted there, exact as a shackle made from the instant before a pendulum dropped. The god stood. The landing groaned under his weight.
"Stay where I can see you," he said. "If you stop moving, or lose sight of me, my reach here collapses. And when I act—"
The charge struck the top of the street before he finished.
The engine came around the bend in a storm of sparks, taller than a house and patched with what it had stolen: blue shutters armoring its left wheel, roof beams bristling from the chassis, a marble lintel driven through the plated prow. Its wheels followed the old demonstration grooves, but the broken paving canted it farther east on every pass.
People jammed the stairs below. A woman dragged a handcart through the entry arch while a boy pushed from behind. Above them, the cracked stone cornice tore loose. Red threads from the engine's drum caught the falling pieces and pulled them sideways, toward the moving chassis.
"Stop those stones," Derva said.
The god raised one hand, then held it there. "I cannot stop a fall. The wall has already let them go."
The cornice blocks swung above the cart like hammerheads. Derva started down the stairs, keeping the god in view through the railings.
"Then what?"
"The charge has hold of broken stone. That hold I can end."
"Do it."
Darkness closed over the red threads. The blocks dropped straight down, smashing the empty doorstep behind the cart.
Derva tried to run after the evacuees and found that the world had thickened around her legs. Her first step took as long as three. The god matched her without changing stride, but each pace he took drew speed out of hers.
"You could have mentioned that first," she said.
"I attempted to." His eyes stayed on the charging engine.
Derva forced her knees to unlock. The engine passed the building close enough to scour plaster from the arch. Its right rear wheel dropped into a new hollow, throwing the prow toward the lower lane. Then it thundered on, over the bridge, toward the sluicehouse.
They followed as fast as Derva's borrowed body allowed.
The street had become six kinds of obstruction. Bedding filled a doorway. A brewer rolled two barrels uphill against the evacuation flow. Someone's geese had settled in the middle of the paving and would not be driven uphill.
"East stair's jammed," a porter told Derva, breathless. "Chest won't turn."
She looked once. "Stand it on end. Take the feet off."
"They're carved on."
"Then leave it. Send everyone over the top and down the west stair."
At the next corner a girl was dragging a chandler's handcart uphill, coils of thin rope heaped on the load. Whatever waited at the sluicehouse, Derva had left every length of her own line on her floor.
"I need one of those," Derva said.
The girl stared at the god, then held out a coil. It felt heavy as anchor chain in Derva's unresponsive hand.
The god reached to carry it.
"Leave it. You'll only take it out of my legs."
He withdrew his hand. A cart piled with chair frames rolled between them. His body went translucent at once; his planted foot passed halfway through a paving stone.
Derva caught the cart shaft and heaved it aside. Painfully slow. The moment she saw him whole again, weight returned to his coat and boots.
"Wall side," she said, and he moved to it.
Behind them came the hollow boom of the engine striking the sluicehouse's outer brace. A lesser impact than before. It had glanced off and reset before its full recorded distance, but the next circuit would begin from a roadway in worse condition.
The lieutenant in charge of the evacuation had occupied the diversion winch halfway down the slope. Four crews strained at its capstan, shifting a buried length of demonstration rail toward the eastern residential lane. Chalked numbers covered the lieutenant's leather sleeve.
"Winchwright." He spoke before Derva reached him. "We can turn it six degrees. Lane is empty. Ninety-one dwellings lost, reservoir and bridge held."
"That lane's all cellars. Put the engine over them and they cave."
"Cellars are nine feet. It drops in and sits there."
"Until it resets. Then it tears out the bridge footing to replace what it broke."
The lieutenant glanced at the god. His mouth tightened, but he did not waste time asking who the impossible man was. "Six degrees. Ninety-one dwellings. It comes down again inside a minute."
"Lock the rail where it is."
"Give me another line."
Derva watched the red glare kindle uphill. The engine's left axle would pass within arm's reach of the winch platform. If the god could end it here, there would be no need to touch the gate works.
"That axle," she told him. "Take it when it reaches us."
The god studied the approaching machine. "It is worn. Not ended."
"It will be under full load."
"Derva—"
"Do it on my mark. Lieutenant, get your crews off the capstan."
The lieutenant did not move. "Six degrees keeps it off the gate."
"Off."
Perhaps it was the god beside her. Perhaps it was the engine filling the street. The lieutenant chopped one hand downward, and the crews scattered.
The engine struck the loosened rail. Its prow yawed; the left wheels climbed the paving. Derva saw the axle flex under the chassis, saw daylight open between the axle and its bearing, and gave the order.
The god closed his hand.
All motion went out of Derva.
Her lifted heel hung above the stones. Breath stopped halfway into her lungs. Around the god's fingers, darkness gathered and slipped from the axle without purchase. The metal flexed, screamed, and held. Then the wheel slammed down. The engine tore the diversion winch from its bed and dragged the capstan away in a shower of bolts.
Derva fell when her body returned to her. The god caught her under the arms, but his grip faded as her eyes squeezed shut. She forced them open. His face resolved inches from hers, ceremony gone, fear plain.
"It had not broken," he said. "There was nothing finished in it. Derva, I could not begin the break."
The lieutenant limped from behind the platform, one trouser leg torn. "Four minutes till it's at the gate again. Winch is gone. Ninety-one dwellings still standing."
Derva got onto one knee. The engine's rear assembly ground past them. In an open gear case, the bronze collar clamped around the drive shaft had split in the winch strike. A snapped crescent of it rattled loose, held in its old position by red light, and each turn of the shaft opened a black crack in the iron beneath.
The god pointed. "That break is complete. The charge treats the pieces as joined."
Derva almost told him what to do again. Her mouth formed the first word.
She swallowed it. "Which pieces?"
"The bronze collar and the drive shaft."
"If you end the joining, what still turns?"
"The shaft, badly. Until something heavy strikes it at the crack."
Derva pushed herself up off the paving. "End the joining. Nothing else."
The god touched two fingers to her shadow. The red light in the gear case went out. The broken collar dropped onto the paving and bounced away. Derva's muscles dragged again, but she was on her feet and walking this time, one heel down, one toe forward, and the god stayed solid.
The exposed shaft began to wobble. Down the slope the engine lurched on, trailing the capstan by a twist of cable, and ground to a stop short of the bridge with its drum still pulsing.
"Sluice gallery," Derva said. She turned to the lieutenant. "I need the west gate counterweight unpinned, two hauling crews on its service line, and everyone else off the bridge."
"That's six hundred pounds off the west gate."
"Not if I dog the manual wheel."
"You'll be in the gallery."
"Yes."
He looked from her to the stalled engine, counting without moving his lips. "Three minutes."
This time he ran before she did.
The sluice gallery was a stone throat built along the reservoir wall. On one side, iron gate wheels rose taller than Derva; on the other, arched service openings looked down onto the bridge and the charge route. The west counterweight hung in its shaft above them, six hundred pounds of black iron cast in the arsenal foundry. Its service line ran through a ceiling block to the manual wheel.
Derva entered with the god at her shoulder and the thin rope across her chest. Her body still answered late. She made every movement continuous: walking while she pulled the coil free, circling the wheel while she knotted the rope, leaning rather than stopping when her fingers failed to close.
Outside, the stalled engine vanished in backward thunder.
Fourth circuit.
The lieutenant arrived with two crews. "Bridge clear. One minute forty."
"Crews on the service line. Then the counterweight pin."
He had the crews on the line before she reached the shaft, and he set both hands to the pin beside hers. "Minute twenty," he said as it began to move. It came free grain by grain. The crews took the strain; rope fibers snapped in tiny reports.
Derva led the thin line through the nearest service arch and around a maintenance snatch block. The block's hook had been driven into the wall to lift gate teeth, not swing weights across a roadway. She tested the anchor with her shoulder.
The god watched the strain travel through rope, block, hook, and stone. "The hook may end first."
"May?"
"Its inner curve is hidden from me."
"Next arch along. You'll see into the throat of it from there, and I'll see you past the wheel. If it starts to open, say so."
He went to the next arch along and turned so that she had his face over the gate wheel's rim.
The charge entered the lower street. Its rumble filled the gallery floor. Derva tied the thin rope to the counterweight's lifting eye and passed its free end to the lieutenant.
"When the prow's past the far end of the bridge, pull. Not before." She had to stop for breath. "Hit the prow and the weight skates off the armor into the parapet. It has to take the shaft. Behind the second wheel. At the crack."
The lieutenant wrapped the line twice around his forearm and sighted down through the arch at the bridge. His lips moved: six wheels, the spacing between them, the length of the prow.
The manual gate wheel shivered under Derva's palm. She needed to dog it the instant the counterweight swung free, or the reservoir would lift the gate. The pawl hung half engaged above the ratchet. Ordinarily she could seat it in one hard movement. Now her fingers took three tries to close on a spoke.
The engine burst onto the bridge. Stone cracked beneath the first wheel. Its prow carried half the district in its armor now: carved fireplace surrounds, shop signs, roof nails gathered into a bristling black hide. The drum beat red in its belly, giving the same order it had given on the first run.
"Hold," Derva said. The crews leaned against the service line. Water hissed around the west gate.
The prow crossed the far edge of the bridge. "Now."
The lieutenant hauled. The crews paid out one arm's length of service line. The counterweight dropped, the thin rope caught it sideways, and it swung out through the service arch.
It struck the wobbling shaft behind the second wheel.
The sound was smaller than Derva expected: a hard iron cough. Then the shaft folded at the crack. The rear wheels drove over the broken metal, twisting the chassis sideways. The engine's prow cleared the bridge and buried itself in the empty inspection yard. Its memory drum kept turning, but no force reached the wheels. Above the service arch, the snatch-block hook split.
"Hook ended," the god said.
"Leave it. The engine?"
He stared into the red drum. Begging had made him look almost human on her landing. Here, with a true ending before him, he stayed solid in her sight while the light around him went wrong. The gallery lamps bent inward. Every shadow in the stone throat pointed toward his hand.
"The drive is ended," he said. "The pattern can be severed now."
Derva's legs were already failing. Behind her, the manual wheel began to turn as the unbalanced gate lifted.
"Do it."
The god reached.
The drum's red pulse stopped between beats.
Derva lost everything except the small forward drag of her left foot. She kept that toe scraping stone while the god drew the last stored repetition out of the wreck. Red lines rose from the engine, thinned to threads, and disappeared into the dark of his palm. Timber and masonry trembled in the chassis but did not fly backward. The engine remained where it had broken.
The manual wheel spun faster. Derva could not raise her arms. She let her weight fall against a spoke. The wheel drove her around with it, once, half again. Her right hand passed the hanging pawl. Too late. On the next turn she hooked it with two fingers. The ratchet hammered against its tip and kicked it loose. Water spread over her boots.
"Derva," the god said.
"Keep—" Her jaw worked after the word. "Working."
He could not hold the wheel without abandoning the engine. He looked once at the lieutenant.
The lieutenant shoved his shoulder beside Derva's. "On three," he called to the crews. "One. Two."
They checked the service line on two. The gate wheel slowed just enough. Derva caught the pawl again and dropped her whole forearm over it. Iron met iron. The ratchet struck, bounced, then seated.
The west gate stopped a handspan open. A shallow sheet of water ran across the gallery floor and out under the service arches, nothing more.
For several breaths, nobody spoke. Rope creaked. The broken engine ticked in the inspection yard.
Then the god lowered his hand.
Motion returned to Derva in painful increments: lungs first, then shoulders, then the cramped fingers locked around the pawl. Her legs remained distant things. She sat down because choosing to sit was easier than pretending she had not fallen.
The lieutenant went to the arch and looked out. "No reset."
"Clear the hauling crews," Derva said. Her words came slowly, but they came. "Then braces on the west gate."
"And the wall?"
"After the gate."
He nodded and began assigning hands. The first brace crew was moving before anyone found breath for cheering.
Derva watched the memory drum until its metal cooled from red to ordinary black. The god stood beside her shadow. He was still fully present, but the gallery lamps no longer leaned toward him.
"Can you still hear it?" she asked.
He listened with his head a little to one side, the way she listened to a cable under load.
"No," he said. "It finished."
"Good." She let her head rest against the wheel. "Go on, then. I dismiss you."
His outline thinned. For an instant she saw the impossible distance behind his face, all those far lamps of worship and the authority they carried. He opened his mouth, perhaps to recover the words proper to a god's departure.
A crewman shouted from the gate shaft, "Which brace first?"
Derva looked away from the god. "East bearing. Nobody touches the wheel until it's shored."
When she looked back, the gallery held only her own shadow.
Feeling returned to her feet as pins and heat. Derva pulled the thin rope toward her, found the broken snatch block at its end, and began checking which pieces could still be used.