Huey paused, and Rector came up beside him, trying not to wheeze, but glad for the brief break. “What? Miss Mercy? I don’t understand.”

“You and Zeke said something about a train, and everybody disappearing.”

“But all those other people didn’t disappear inside here. They just … disappeared. Except for her. She’s been trying to find them, trying to figure out what happened to everybody.”

“Why?”

“Because there were rotters. Outside Seattle.”

“Rotters on a train?”

Houjin’s words took on that tense, impatient quality again. “No, not rotters on a train. But rotters outside the city—all the way out in the Utah Territory, up in the mountains. Miss Mercy thinks they were made when an airship crashed down in Texas.”

Rector had no idea how far away Texas was from Utah, or how far Utah was from Seattle. Quite a ways, he suspected, but he didn’t want to sound dumb, so he didn’t ask.

Houjin resumed walking. Rector kept pace this time, since the way was wide enough to accommodate them both. The streets were not clean, but they lacked the usual thick, wind-heaped detritus of the busier blocks, so the boys’ boots made less noise than their chatter as they crept up the hill.

“How does that work?” Rector asked. “How does an airship in Texas make rotters in Utah?” He was almost proud of himself for how un-dumb that sounded.

“The airship was carrying Blight concentrate for processing down in Mexico. It crashed right on top of people, and turned them. Just like that. Just like the sap does, if you use it too long…”

“Hey!”

“What? I’m not accusing you of anything—only pointing out the connection. The sap kills people the same way as the gas, but it takes a lot longer. And Miss Mercy’s seen lots of drug users at the end of their lives, on the battlefields and in the hospitals. She probably knows more about it, from more angles, than anyone in the world. But when she tried to reach the people from the Dreadnought … it was like they’d never existed.”

Rector didn’t like the sound of that, and he wasn’t entirely sure why. “Or like someone took them away?”

“That’s one theory. That’s her theory, anyway. She thinks somebody important wants to keep the sap running, and keep the soldiers stocked up.”

“Why the hell would anybody want to do that?”

Houjin shrugged. “It usually comes down to money.”

“Money,” Rector echoed thoughtfully.

His companion drew up to a sudden stop, smacking him across the chest with his arm to get his attention.

A faint hum rumbled overhead. Nothing too loud, nothing too close.

Rector guessed, “Is that one of the pump rooms?”

“No, look higher. It’s the Naamah Darling, see?”

He couldn’t see a damn thing, so he grunted noncommittally.