The door shook again, but it did not open.
Iven and Pellan set the drill frame down without dropping it. Kesh approached the door, stopping well short of it, and held her lamp low. The latch remained in place. A narrow line of pale dust sifted from beneath the threshold.
“Could be the pipe on the other side,” Pellan said.
“Could be,” Kesh agreed. “We’re not opening it to find out.”
Elian had dropped one of the drill bits. It rolled toward the door, struck the threshold, and stopped. He bent to retrieve it.
“Leave it,” Iven said.
Elian straightened. “It’s one bit.”
“It’s one bit on the wrong side of the room.”
The door moved inward a fraction, then settled back against the frame. The latch made a dry click.
Elian stepped away from the bit. “I see your point.”
They lifted the drill frame again and carried it into the passage. Kesh walked backward for the first few paces, watching the door, then turned and followed them. Sera stayed near Elian, who held the box of bits and the rolled map against his chest.
The line they had tied at the entrance ran along the wall, looped around each support. It should have made the return straightforward. At the first bend, the line disappeared into a wet mass that had spread across the floor while they were inside.
Pellan swore. “That wasn’t there.”
The mass was a layer of fibrous growth mixed with water and pale sediment. It had pushed through a gap beside a pipe, carrying the line with it. The line had not broken, but it was pinned beneath the material.
“Can we cut it?” Elian asked.
“We can,” Kesh said. “Then we lose the part that leads back.”
“We know the way.”
“We knew the way in. I prefer not to rely on memory when the floor has started moving.”
Iven set down his end of the drill frame. The growth was warm to the touch through his glove and yielded slightly under pressure. It did not feel like mud. He found the line where it entered the mass and pulled gently. The cord moved a little, then caught.
“Something’s holding it.”
Sera crouched beside him. “There’s a seam underneath.”
“Can you see it?”
“I can see where the water is coming out. The seam is a guess.”
Pellan set down the other end of the frame. “There’s a drain under that section. The last crew said it backed up.”
Iven thought of the loose grate they had passed. If water had built behind it, the moving wall could have pushed the growth out through the gap. He did not need to understand the entire mechanism to know they should avoid tearing at it blindly.
“Can we lift it?” he asked.
Kesh tested the edge with her hooked pole. The material rose an inch and dropped back. Beneath it, a narrow channel carried water toward the drain.
“We can move a small section,” Kesh said. “Not all of it.”
Iven tied a short loop of rope around the exposed line and ran it through a metal ring fixed to the wall. He seated the winch pattern and pulled gradually. The line tightened. The fibrous layer lifted where it crossed the channel, revealing the cord caught under a bent grate.
Pellan wedged the hooked pole beneath the grate and levered it up. Sera pulled the line free. When Iven released the tension, the material settled back, and water resumed running beneath it.
“Mark the drain,” Elian said, making a note on his map.
“I’ll mark it with a picture of a man swimming,” Pellan replied.
They retrieved the drill frame. Iven found the load easier to manage if he walked backward through the narrow bend while Pellan faced forward. Kesh kept the lamp where both could see their footing. The frame’s metal legs struck the wall twice, each clang louder than the last in the confined space.
“Sorry,” Pellan said.
“Don’t apologize to the wall,” Iven replied. “It won’t listen.”
At the next junction, Elian stopped. The chalk mark they had made on the way in was still on the support, but the arrow pointed toward a passage Iven did not remember.
“Did we turn left here?” Elian asked.
“We went through the low arch,” Pellan said.
“There are two.”
One arch opened onto a dry passage. The other had water shining on the floor. Both were low. Both had a pipe above them. Iven could see why a map copied from an old report might have lost track of one.
Kesh pointed to the line. It led through the wetter arch. “That’s ours.”
They followed it, carrying the frame above the shallow water. Halfway through, Sera stopped and raised her hand. Iven set the frame down with Pellan and looked back.
“The air changed,” she said.
He had not noticed until she spoke. The air had become warmer and carried a sharp odor through the mask. He activated the filter pattern briefly. The smell remained.
“It’s not just dust,” he said.
“No. Masks on tight. We don’t stay here to identify it.”
Kesh held her lamp near the floor and then higher, watching the flame. It burned steadily, but that did not prove the air was safe. They had agreed on that before entering. She moved to the front and checked the next section of passage.
A vent cover had fallen from the wall. Beyond it, a narrow shaft carried warm air upward. The cover lay across the floor, one corner bent. Without it, air from the shaft flowed directly into their route.
“Can we put it back?” Pellan asked.
“Can we do it quickly?” Sera asked.
Iven examined the mounting. Two screws remained in the wall, but the lower edge had broken away. The cover would hang from the upper screws and leave a gap at the bottom. It might still reduce the flow enough for them to pass.
He lifted it with Pellan’s help. Kesh held the lamp while Iven seated the upper slots over the screws. The cover swung inward and struck the wall. Pellan pressed the lower corner against the frame, but it would not stay.
Iven took a piece of wire from his coat and threaded it through an intact hole. He looped the wire around the pipe bracket beside the vent and twisted it tight. The cover settled against the opening. Air still leaked around the damaged edge, but the direct flow stopped.
“Temporary,” he said.
“Everything we do down here seems temporary,” Pellan replied.
“That’s why people keep hiring us.”
They passed the vent without stopping. The air improved after the next turn. Sera made each of them drink a little water, then checked Pellan’s eyes and asked him to name the tools in his belt. He named them, added two that were not there, and admitted he had done it to see whether she was listening.
“I was,” she said. “Now name the missing ones.”
He named them correctly.
Elian sat on a low ledge while Iven retied the drill frame for easier carrying. The surveyor had a scrape on one hand where the box of bits had shifted. Sera cleaned it and wrapped it with a narrow strip of cloth.
“You don’t have to do that,” Elian said.
“I know.”
“It’s a scratch.”
“It’s also on the hand you’re using to carry metal through a dirty passage.”
He held still while she finished. “My father says people complain when a survey takes too long. They complain more when the map is wrong.”
“Does he listen when the map is wrong?” Iven asked.
Elian looked at the line drawn through the missing ladder. “He listens to the survey office.”
“That wasn’t the question.”
“No.” Elian rolled the map carefully. “I don’t know whether he listens to every person who uses it. I haven’t asked enough of them.”
Kesh returned from checking the next turn. “There’s a noise ahead. Not the small scrapers.”
Everyone stood.
“How many?” Pellan asked.
“I heard two sets of movement. Maybe more.”
“Can we use another route?”
Elian unrolled the map again. The only marked alternative led upward through a shaft whose ladder had been removed. He pointed to a narrow maintenance opening near it.
“That may connect to the upper passage.”
“May?” Iven said.
“The report says it was used twelve years ago.”
Kesh considered. “We can look without taking the frame in. Leave it here with Pellan. Iven and I will check the opening.”
“I’ll go,” Elian said.
“You’ll stay with the map,” Kesh replied. “If we come back and say it connects, you’ll need to mark it.”
Iven took his lamp and followed Kesh through the low opening. They moved on hands and knees for several yards. The passage smelled of damp stone and old oil. A pipe crossed the floor, forcing them to crawl over it one at a time. Beyond it, the ceiling rose enough for them to stand.
A door blocked the far end. Its lower hinge had broken, leaving it tilted into the frame. Kesh pressed against it. It moved a little and stuck.
“Can you repair that quickly?” she asked.
Iven inspected the hinge. The pin had slipped halfway out. The mounting plate was sound, but the weight of the door had bent the pin against the frame.
“I can put it back if we lift the door.”
They positioned a short bar beneath the lower edge. Kesh pressed down while Iven drove the pin out with his hammer. The door shifted. Iven caught it with his shoulder, then used a small plate brace against the frame to hold it in position while Kesh moved the bar.
The bent pin would not go back in. Iven straightened it as much as he could against the floor, then replaced it with a short bolt from the drill frame’s spare fittings. The bolt was not ideal, but it held the hinge while they opened the door.
On the other side lay a broad maintenance passage with a raised walkway. At its far end, Iven could see the familiar mounting points for the removed ladder.
“It connects,” he said.
Kesh stepped through and listened. No scraping came from this passage. She tied a short strip of cloth to the door handle so they could find it from the other side.
They returned to the group. Pellan had moved the drill frame closer to the opening, and Elian had marked the possible route in pencil rather than ink. When Iven confirmed it, he changed the line to a solid one.
“Can the frame fit?” Sera asked.
“We’ll have to turn it on its side,” Iven said. “And take one leg off.”
Pellan looked at the bolts. “I can do that.”
The noise came again from the passage they had planned to use. This time it was closer: a series of hard contacts against the floor, followed by a low scrape.
Kesh raised her pole. “Take the leg off now. Quietly.”
Pellan set down his bar and reached for a wrench. Iven knelt beside him. Together they loosened the first bolt, then the second. The leg came free. Elian took it and crawled into the opening ahead of them.
The third bolt would not turn. Pellan adjusted his grip. Iven held the frame steady while he pulled. The bolt moved a fraction, then stopped.
Behind them, something struck the wall.
Sera moved her lamp toward the sound. A pale shape appeared at the bend, low to the ground, with mineral plates along its back. Another moved behind it.
“Leave the bolt,” Kesh said.
Pellan looked at the frame. “It won’t fit.”
“Then we make it fit,” Iven said.
He took the wrench, braced the frame against the floor, and put the piston pattern into his free channel. The creatures were still at the bend. Kesh stood between them and the group, pole held low. Iven had a few seconds, no more, to decide whether the bolt would turn or the frame would have to be abandoned.