Sera opened the familiar clinic above the former bathhouse while Brin went to bring the missing worker’s partner. Iven followed her upstairs, keeping one hand against the shallow scrape on his side. His coat had torn during the fight beneath Derrit’s hatch, and the muffled street sounds had not yet returned to normal after the bell pulse.
The room smelled of boiled linen, lamp oil, and the sharp citrus scent he remembered from his earlier visits. The bed stood under the window; the washbasin leaned on its three mismatched legs. Sera set her case down and held out a hand.
“Your arm. I want to see whether the dressing survived that climb.”
He rolled up his left sleeve. The graft’s raised branches still showed beneath the skin. Sera had already traced the likely feedback to damaged return branches, though the precise path remained to be mapped. She had not promised to fix it without understanding it.
She washed her hands, then pressed two fingers lightly beside the graft. “Any numbness?”
“My ears.”
“In the arm.”
“No.”
She took a small metal fork from her instrument cloth and struck it against the edge of the basin. Iven saw the vibration. A thin, uncertain note reached him a moment later, as though it had taken a less direct route through the room.
“Tell me when it stops,” she said.
He watched her mouth, then nodded. She held the fork near his left ear. He heard a thread of sound, lost it, and lifted his right hand. She repeated the test on the other side. That note lasted a little longer.
“The ringing you made at the gate hasn’t done your hearing any favors,” she said. “But this is better than the last time I checked.”
“That’s good.”
“It’s information. Good would be knowing exactly how the damaged return is sending vibration into your ears.”
He sat on the edge of the bed. “You told me it was feedback.”
“I told you what it resembles. A loose wagon wheel makes a noise. That doesn’t mean I’ve seen the axle.”
Iven considered the lines on his arm. “You’re telling me I stole a wagon.”
“An expensive one. You haven’t learned to drive it.”
A knock sounded below. Brin came upstairs with a folded slip, having brought the worker’s partner to the street outside. Iven had heard him announce the missing person at the clinic stairs; now the boy had a name and a work location.
“Filter bank nine,” Brin said. “Her name’s Maret Dunn. The other two came out.”
Sera took the slip. Two names were checked off and one was not. She sent Brin to bring the partner up and find where the injured crew member had been taken.
Iven glanced at the shelf of supplies. “How bad is bad?”
“Depends what the air is bad with.” Sera opened a cupboard. “Dust, gas, or lack of oxygen. A mask helps with one and may do nothing for the others.”
“You have masks?”
“Two that I trust. One has a split seal.”
“That sounds like one.”
“It was two this morning. You can count while you mend it.”
His waist rope had been cut beneath the feed hatch. Sera pointed out a spare clinic coil, and he set it beside the door to borrow for the search; he would buy a replacement of his own when he had time. His side hurt when he bent, but the bandage remained dry.
The partner came up before Iven could ask how he had acquired a job. Her name was Lill, and she stood just inside the door with both hands clasped so tightly that her knuckles had gone pale. She wore a gray work apron over her clothes. A strip of green thread was tied around one wrist.
“Maret left after the second meal,” she said. “She said she would be back before the bathhouse opened.”
Iven looked at the old sign through the window.
“The new one,” Lill said, following his gaze. “On Copper Walk. I work there. We were going to eat together.”
Sera pulled a chair forward. Lill sat only when Sera put a hand on the back of it.
“Do you know her route?”
“Filter bank nine. They’re changing the inner screens before the next heat adjustment. She checks the pressure and writes down what they find. She doesn’t usually go into the bank itself.”
“Did she say anything about the work?”
Lill rubbed at the green thread. “She said someone had been drilling near it. They were supposed to stop before the inspection. She complained because the noise made the gauges jump.”
Iven caught Sera looking at him. He thought of the pale thing he had seen inside, of its mineral plates and the way it had turned toward the damaged passage. He had no wish to explain it to Lill while she sat waiting for news of a person who might be hurt.
“Did Maret carry a lamp?” he asked.
“A little hand lamp. She hates the company ones. Says they always run out when a supervisor is watching.”
That sounded like someone he would like, provided she was still in a position to complain about supervisors.
Sera asked a few more questions, then sent Brin to Copper Walk with Lill to collect a scarf and any other identifying belongings. “If she comes back on her own, I want to know at once,” she said. “If anyone tells you she’s dead, ask who saw her.”
When they had gone, Sera set two masks on the table. One was a heavy canvas hood with a glass eyepiece. The other was smaller, built around a rigid mouthpiece and a circular filter canister. A seam had split where the canister joined its collar.
Iven picked it up. The outer cloth was gritty. He could see a gap between the rubber gasket and the rim.
“Is the filter itself sound?” he asked.
“We’ll find out after the seal holds.”
He turned the canister. Someone had patched the casing twice. The older patch was neat; the newer had been done with the wrong thread and pulled the material into a fold. He opened the seam with his awl and laid the pieces on the table. Sera placed a clean cloth under them before he could put a blackened screw directly on the wood.
“Your table?” he asked.
“My landlord’s. I’d prefer he complain about the rent.”
He removed the damaged gasket. It had gone stiff with heat, and a shallow crack crossed its face. Sera produced a box of scraps: leather, rubber, and a few pieces of soft woven packing. Iven selected a strip of rubber, checked its thickness against the groove with his folding gauge, and cut it a fraction wider than he needed.
“Where did you learn this?” she asked.
“People keep wanting air.”
“I meant the work.”
“On pumps. If a seal lets the wrong thing through, the machine tells you. Usually by flooding your boots.”
He fitted the new ring around the collar. The ends met poorly. He trimmed one, warmed both with the kettle’s side, and joined them with a narrow band of adhesive Sera supplied. While it set, he opened the canister itself.
Inside were layers of packed fiber and charcoal. The fiber was gray and clogged near the intake. A metal retaining mesh had bent inward, allowing the packing to shift and leave a path along the edge.
“There’s your second problem,” he said.
Sera leaned close. “Can you replace the material?”
“The fiber, yes. The charcoal depends on what you have.”
She brought a jar from a high shelf. “Fresh. It won’t take every gas out of the air.”
“I heard you the first time.”
“Your hearing suggests otherwise.”
He looked up. Her expression stayed perfectly composed. It took him a moment to realize she had made a joke.
“Cruel,” he said.
“Efficient.”
He washed the mesh, straightened it against the edge of the table, and packed the canister again in measured layers, leaving enough room for air to pass. Too tight, and the wearer would fight for every breath. Too loose, and dust would find the gaps. He sealed the casing, fitted the collar over the new gasket, and tightened its screws in alternating turns.
Sera brought a shallow bowl of water. Iven covered the intake and blew gently into the mouthpiece. A line of tiny bubbles appeared at one edge of the collar.
He swore. Sera said nothing, which was worse than agreement.
The gap came from a nick in the metal, almost hidden beneath the screw head. He took the assembly apart again, filed the nick smooth, then cut a narrow packing strip to seat beneath it. The second test held. Sera laid the hood beside it and checked that its valve still moved freely.
“For dust,” she said. “Not a promise against every gas.”
“I know.”
“For someone who keeps saying that, you seem offended when I repeat it.”
He put the mouthpiece on. The repaired seal settled against his face, and he drew a cautious breath. There was resistance, but not much. The air smelled faintly of charcoal and hot rubber. He stepped to the window, where soot had collected along the sill, and tapped it with the handle of his hammer. A small cloud rose. He breathed through the mask. The taste of old dust stayed outside.
Something shifted beneath the graft in his left arm.
He froze, hand still raised. The sensation was not a voice and not a thought. It was closer to the moment a gear caught its neighbor’s teeth: a small, definite engagement, followed by the feeling that a path existed where there had been none.
Sera noticed. “What?”
“The arm.” He pulled the mouthpiece away. “It did something when I tested it.”
She examined the graft without touching it. “Describe it.”
He tried. The more words he used, the less certain he sounded. In the end he held up the filter. “Like this has made an impression.”
“Perhaps it has.”
“You’re the expert.”
“I am. That’s why I won’t tell you I know before we test it.”
She took a pinch of fine chalk from a jar, carried it to the open window, and put a folded cloth over her own mouth. “No masks for this. If you feel faint, stop. Do not take a deep breath to prove a point.”
“Do I often do that?”
“I met you at a gate you had just rung with a damaged graft. I have a working opinion.”
Iven leaned near the sill. Sera scattered the chalk into the daylight. He held the memory of the filter in his attention—not its shape, exactly, but the way air had passed through the packed layers while the grit stayed behind.
His left forearm warmed. The chalk drifted toward his face, then curled away around a small clear space no larger than his head. A few grains reached his nose. He sneezed and lost the effect.
Sera watched the rest settle. “Again, if you have enough in you.”
He tried once more, with less force. The clear space held for several breaths. This time he let it go before he lost it. He felt slightly hungry, which seemed an unreasonable price for having just cleaned the air he was breathing.
“A filter,” he said.
“A small one.” Sera set down the chalk. “And it won’t make oxygen where there isn’t any. It may give you a little more time against dust. It doesn’t replace the mask.”
He rubbed his arm. He still had the bell, and he could still feel the pull he had learned from the hand winch. Now there was this third thing, quieter than either. It wasn’t much to look at. Neither was a gasket, until the wrong one failed.
Brin came up the stairs again, breathing hard. He had Lill’s green scarf tucked under his belt.
“The worker they carried out is awake,” he said. “He says Maret didn’t get to the inner turn.”
“Where did she go?” Sera asked.
“He says the floor opened under the inspection platform. She went down through it. They heard her knocking afterward.”
Iven took the mask off the table. “How long ago?”
“Long enough that he thought the knocking had stopped.”
Sera collected her case. “Did he tell you what made the floor open?”
Brin hesitated. “He said something came up underneath it.”
The room seemed very quiet. Iven couldn’t tell whether that was his hearing or the pause between Mercy’s steps.
Sera handed him the repaired mask. “Bring your rope,” she said. “And don’t spend the filter before we know what we’re breathing.”
Iven put the mask over his shoulder. He had wanted the restorer’s graft because it might give him a way through a locked gate. The gate was open now. Beyond it, the city had apparently found another way to swallow people.
He followed Sera downstairs.