The old man's name was Ferris, and he had lived in Lower Fifth for sixty-one years, which meant he had been alive for everything that had happened in this district and could be persuaded, with enough time and the right questions, to remember most of it.

He sat on a folded blanket outside his building's entrance the way he sat every morning when the cycle light was sufficient, a posture that had become structural over decades — back against the stone, legs extended, hands loose in his lap. He had the quality of stillness that very old people sometimes developed, the kind that was not passivity but economy, the conservation of movement for things that required it.

Alden had found him through the Underways contact network, which maintained, among its other functions, a mental map of who in the lower districts had been present for which events and could be trusted to speak about them. Ferris had been in Lower Fifth during Ash Winter. He had been thirty-four years old, working the heating maintenance rotation, which meant he had been one of the people trying to keep the district's shared heating systems functional during the period when they were most needed and most likely to fail.

He remembered everything about Ash Winter. He remembered it the way people remembered things that had marked them deeply — with the specific, unsentimental clarity of someone who had processed the experience fully and no longer needed to protect himself from it.

“The coal ran out on the eighth day,” he said, when Seren asked him to describe the period. “Not ran out — was redirected. The allocation shifted to High Ring residential because of the cold event, and Lower Rings got the remainder, which was not enough. We knew it wasn't enough. Everyone knew. But the allocation form had been completed correctly, so officially everything was in order.”

He described the following weeks with the same precision: the progression of the respiratory illness through the densely populated blocks, the collapse of the triage station system around the fourteenth day when the intake exceeded capacity by a factor of three, the informal networks that formed to distribute food and fuel and information in the absence of functioning official channels. He described the dead — not statistically, but individually, the way someone described neighbors.

“The Records people came eventually,” he said. “To count. They always come to count. But the counting takes time, and the people don't wait.”

Seren was writing in her ledger. Alden was listening with the stillness he used when he was absorbing rather than analyzing.

“Were there any inspection teams that came through during that period?” she asked. “Not medical. Technical — infrastructure or structural.”

Ferris thought about this. “Yes. About two weeks in, when the worst of the illness was passing but before the cleanup had really started. A group, maybe six or eight people. Marked, all of them, which you noticed because Marked inspection teams didn't usually come this far into Lower Rings unless something official required it.” He paused. “They weren't there for the people. They walked past the sick, past the dead outside the triage station, and went to the walls.”

“The walls,” Alden said.

“The structural walls. The ones that go down into the ground — the base walls, where the ring levels meet the bedrock. There are access points for maintenance at intervals, mostly used by the deep drainage crews. These people had keys to those access points. They went in, spent time in the sub-levels, came back out. Did it at four or five locations in Lower Fifth and Lower Ashfield that I know of.” He looked at his hands. “They were measuring something. Or looking for something. They had instruments I didn't recognize.”

“Did you speak with them?” Seren asked.

“No. You didn't approach that kind of group uninvited. And they weren't interested in speaking with anyone here.” He was quiet for a moment. “There were people dying outside the triage station. These people walked past them to look at the walls.”

Seren noted this.

“The access points they used,” she said. “The sub-levels. Do you know what's down there?”

“Bedrock, mostly. Old drainage infrastructure. And —” He stopped. “This is something I was told by an old maintenance man, years before Ash Winter. He said the sub-levels in certain parts of Lower Rings were different from the rest. The stone was cut differently. Finer, older. He said if you went deep enough, the walls stopped looking like construction and started looking like something else. He didn't know what.”

Alden's posture had shifted slightly — the almost-imperceptible change she had learned to read as heightened attention.

“And after the inspection team left,” she said. “Did anything change?”

Ferris considered this for a long time. “There was a strange thing,” he said slowly. “In the weeks after they came through. Some people — not many, not all of them, just a few — started saying they didn't understand why they'd always been afraid of the Skyline. Not that they wanted to go there. Just that the reason for being afraid of it had gone unclear. Like when you wake up from a dream and you remember you were afraid of something in it but you can't remember what it was.”

He paused.

“It went away after a few weeks for most of them. They stopped saying it. And then it was as if they'd never said it. I thought about it for a while and then I stopped thinking about it too, because there was enough else to think about.” He looked at Seren. “Why are you asking about this?”

“I'm doing a cross-reference verification for the Ash Winter records,” she said. “Inconsistencies in the documentation from that period.”

This was true. It was also the least important true thing she could have said about her reasons for being here.

Ferris looked at her for a moment with the attention of someone who had been alive long enough to know when they were being told the truth selectively. Then he nodded once and looked back at the street.

“The walls are still there,” he said. “Whatever they were looking for, if they found it, they didn't do anything about it that anyone could see. Or they found it and decided not to do anything about it. Or they didn't find it.” He paused. “Or they found something they weren't expecting and that changed what they were going to do.”

Seren closed her ledger.

“Thank you,” she said.

“Don't thank me,” he said. “Just write things down correctly.”

On the walk back through Lower Fifth, Alden said: “The sub-levels. The walls where the Vault meets the bedrock.”

“Cael Vaelor-Ross was at Ashfield shaft. The deepest accessible point in the Lower Rings mining infrastructure. If the same team was checking structural walls at multiple Lower Rings locations —”

“They were mapping something,” Alden said. “Or confirming something.”

“Or both.” She looked up at the Vault above them — the grey-silver dome, unchanging, the same at every angle. “And the people who were nearby afterward forgot why they were afraid of it.”

Neither of them said the obvious thing. They walked back through the district where Alden had grown up, past the walls that went down into the ground, past the access points to the sub-levels, under the sky that had sheltered them for as long as either of them could remember.

In her ledger that evening, she wrote: *Ash Winter inspection team — structural walls, bedrock access points, multiple Lower Rings locations. Vaelor collateral involvement confirmed through Ashfield. Post-visit memory effect: temporary loss of fear-association with Skyline in nearby residents. Duration: weeks. Mechanism: unknown. Vault and memory — connected?*

She underlined the last line and sat with it for a long time.