The xưởng had been abandoned for at least a decade before they found it.

Alden knew about it because Alden knew about most things in Lower Rings that other people did not know about — gaps in fences, loose boards in walls, the specific angle at which a padlocked door could be lifted slightly off its hinges to disengage the bolt. He had a talent for finding the places that the city had forgotten. Seren had once asked him how he always knew where the forgotten places were, and he had thought about it for a moment and said: you look for where the light doesn’t reach. Things that haven’t been touched in a while stop catching the light right.

They were ten years old. It was the third winter they had spent navigating Lower Rings together, the three of them — Seren and Alden and Cassian — the particular unit they had become through the accumulated logic of proximity and survival. They lived within four blocks of each other. They were all Unmarked. They were all the right age to be useful enough to run errands but not old enough to be assigned formal labor yet, which meant they occupied the specific freedom of children who were not worth supervising.

The abandoned charcoal works sat at the edge of the district, past the last row of active workshops. It had been a warehouse once, before the coal consortium had shifted its operations closer to the main shaft lifts and left the outer facilities to deteriorate quietly. The exterior looked like collapse — sagging roof line, boards warped with years of moisture, the kind of building you walked past quickly because it looked like it was considering falling on you.

Inside was different.

Alden found the entry point: a section of the eastern wall where the lower boards had rotted through at the base but the upper structure remained sound. If you knew to press in at exactly the right spot, the boards swung inward like a low door. You had to duck. Once you were inside, you could stand upright.

The interior was a single large space, the ceiling high enough that the roof beams disappeared into shadow. Light came through gaps in the boards — thin, diagonal lines of it, the grey-yellow light of Vault shine filtering down from above. The floor was covered in decades of charcoal dust and the scattered remnants of the warehouse’s original contents: broken crates, coils of old rope, the chassis of a cart missing its wheels. It smelled like age and old fire.

Cassian stood in the middle of it and turned a slow circle with his arms out.

“This,” he said, “is ours.”

“It belongs to the consortium,” Seren said.

“The consortium left it. Things that are left belong to whoever finds them. That’s how finding works.”

“That is not how property law works.”

“Do you know what else doesn’t work?” Cassian spread his arms wider. “The consortium’s claim to this building, apparently, because they haven’t been here in ten years.” He looked at Alden. “Right?”

Alden was examining the ceiling. “The load-bearing beams are still solid. The roof sags but it won’t fall. Not this season.” He paused. “Probably not this season.”

“Definitely ours,” Cassian said.

They made it theirs over the course of the following weeks, in the way that children make things theirs — gradually, through the accumulation of small changes and the investment of time. Alden identified which sections of the floor were stable. Cassian began collecting materials from the scrap heaps and refuse piles that accumulated at the edges of the workshops: pieces of broken glass, scraps of mica from the lens-grinding district, a cracked mirror face he had found behind one of the pawn houses. Seren contributed a pot of paste adhesive she made herself from boiled flour and a length of cord she had unraveled from the binding of a damaged shipping crate.

The ceiling project was Cassian’s idea.

He had been standing in the doorway of a Crown Ring establishment — one of the food vendors that catered to High Ring foot traffic, that had a sign in the window saying Marked clientele preferred in the particular phrasing that meant everyone else would be served last if at all — watching the light through the upper windows illuminate a hanging glass ornament above the counter. The ornament caught the light and threw it in fragments across the ceiling. Cassian had stood there for a full minute before the vendor noticed him and told him to move along.

He described the ornament to Seren and Alden that evening with unusual precision, the way he described things when he had decided he wanted something.

“If we put things on the ceiling,” he said, “the light would do that.”

“Our ceiling is thirty feet up,” Seren said.

“Alden can get to thirty feet.”

Alden, who had been sitting against the wall with his eyes closed, said: “Alden can get to thirty feet if there’s something to climb.”

There was something to climb. The original warehouse had interior scaffolding supports still bolted to the walls — iron brackets at intervals, the anchors for shelving systems that no longer existed. Alden tested each one before committing his weight to it. Several failed. Several held. The ones that held formed a route up the eastern wall to a section of roof beam that ran the width of the space, close enough to the high point of the ceiling to reach the blackened wood with an arm extended.

It took them three evenings.

Alden made the climbs. Seren mixed the adhesive and handed up pieces on the end of a cord. Cassian sorted the glass and mica fragments by size and reflectivity, which he did with an attention to detail that he applied to almost nothing else in his life. When a piece was too large, he broke it smaller against the floor, then checked the edges with his thumbnail and discarded the ones that he felt might cut through the cord during the lift.

They went from largest to smallest, working outward from the center beam. The pieces caught even the dim filtered light and threw it in small arcs across the walls — not bright, not like anything Seren had seen in High Ring windows, but present. Unmistakably present.

On the last evening, when they had used everything they had collected, the three of them lay on their backs on the stable section of floor and looked up at what they had made.

The Vault shine came through the gaps in the boards at its usual angle — the diffuse grey-yellow that passed for daylight in Lower Rings, which had less access to the dome’s luminescence than the upper tiers. But the fragments caught it and multiplied it, and for a few minutes in the late afternoon when the angle was right, the ceiling of the abandoned charcoal works looked like something that might, in a certain generous light, be called a sky.

Cassian said: “If Crown Ring has stars above them, we have stars too.”

Seren said: “Those aren’t stars.”

Alden was quiet for a moment. Then: “As long as you can look up and see light, it’s enough.”

None of them said anything after that for a while.

This was the place they called Our Little Sky.

It was also the place where Seren first noticed the way Cassian watched her when she laughed. She was not sure, at ten, what to do with the noticing, so she filed it alongside the other things she was not sure what to do with and left it there.

It was the place where Alden taught her to cross the gap between rooftops — the section of collapsed wall near the warehouse that left a three-foot jump between the warehouse roof and the neighboring workshop roof. She was afraid of the height and refused to say so. He stood on the far side and said: don’t look down. Look at where you want to land. She had asked what happened if she fell. He had said: I’m standing over here, aren’t I? She had jumped. He had caught her arm on the landing.

It was the place where they made the promise.

They were lying on their backs again, some months after the first time. The ceiling had lost two of its larger pieces to a winter storm that had forced boards loose and let in rain, but the rest remained, and the pattern they made was still recognizable as intentional.

Cassian said: “If one of us disappears, the other two have to find them.”

He said it lightly, the way he said things he meant seriously. It was a skill he had.

Seren said: “What counts as disappearing?”

“You’ll know.”

She thought about this. “All right.”

Alden did not say anything for a while. When he did, he said: “I just need the two of you not to disappear.”

Cassian held out his hand, palm down, in the center of their rough triangle. Seren put her hand on top of his. Alden put his hand on top of hers, last, the way he always did things — waiting to see that the others had committed before he committed, which was either caution or loyalty depending on how you looked at it.

In the present, eleven years later, Seren sat in the Ash Annex with two hundred and thirty-nine records remaining and the backs of her eyes feeling like fine sand, and she looked up at the ceiling.

Bare stone. Nothing catching the light.

She picked up her pen.