“Maybe someday he’ll make a lighter version.”

Squiddy said, “I heard he was working on it, but if he ever made a new one, he didn’t let me near it. Are you ready?”

She held up her mask and said, “Sure am.”

He donned his globe-shaped mask and it gave him the look of a lollipop. “Let’s go then.”

Briar strapped her own mask onto her head as she followed him. It seemed like she’d only just pulled it off, but she understood the necessity and — against all expectations — she was almost growing accustomed to it.

Through a dark warren of corridors she hiked, down another stretch of poorly repaired staircases and deep into a grated level where the hum of machinery filled her ears.

Squiddy wasn’t a man who was often asked to play tour guide, so he didn’t give much in the way of highlights. But he did think to mention, “We’re putting more filters down here.” He gestured at the metal latticework under his feet. “It’s an experiment.”

“What kind of experiment?”

“Well, see, right now if we want to keep clean air in the safe spots, we have to pump it down from all the way up over the walls. But that China-boy said maybe we didn’t need to do that. He says maybe we can clean the dirty air as easy as we can pull in clean air. I don’t know if he’s right or not, but some of our people think it’s worth a try.”

“Pumping down all that air must be a real chore.”

“So it is, so it is,” he agreed.

The grates beneath their feet clanged under their steps, and before long they gave way to a landing with three equally barricaded doors. Squiddy adjusted his massive headpiece and reached for one of three levers that were fixed in the floor.

He told her, “This is as close as we can get from inside, so here’s the end of the line. We leave and come back through that one in the middle.” He pointed at the door. “You can’t see any of these doors from the outside. We were real careful with it. It all had to be sealed real tight, because the gas is worst over here.”

“Of course,” she said. “It would be worse, here at the center.”

“Are your filters new?”

“I changed them out just before we left the Vaults.”

He gripped the lever and leaned against it. “Good. Because that eight- or ten-hour rule? It’s not so helpful over here. Those filters won’t work longer than a couple of hours, maybe two or three. We’re going down close to the crack.”

“We are?”

“Sure we are.” The lever bent all the way back, almost to the floor. With it, a chain was drawn somewhere out of sight, and a crack appeared around the center door. “It’s right underneath the old First Bank. That’s as deep as the Boneshaker ever got, and that’s where the worst of the Blight seems to be. That’s the bad news.”

“You say that like there’s good news,” Briar observed as the door grinded back, out into the crushed old blocks where the banks used to be.

“There is good news!” he insisted. “The good news is that there aren’t half so many rotters down here as there are farther out. The gas eats them right up, so they stay away — or the ones that don’t, don’t last too long. That reminds me. You might want to fasten up that coat. You’ve got gloves, don’t you?”

“Yes,” she said, wiggling her fingers to show them.

“Good. Pull your hat down tight, too. Over your ears if it’ll fit. You don’t want any skin showing if you can help it. It’ll burn you,” he said solemnly. “Just like knocking your hand on a stove. It’ll turn your hair, too, and you’ve already got a bit of gold in it.”

“It’s orange,” she said dully. “It used to be black, but it’s getting those orange stripes from all the rain with Blight in it.”

“Tuck it down into your collar if you haven’t got a scarf. It’ll protect your neck.”

“Good plan,” she said, and she did as he suggested.

“Are you ready?”

“I’m ready.”

His sharply carved face wobbled behind the imperfect curve of his mask’s glass front. He said, “Let’s go then. Keep as quiet as you can, but don’t worry yourself too bad. Like I said, we’ll mostly be alone.” He gave her Spencer a pointed stare. “Jeremiah says you’re a real good shot.”

“I am a real good shot.”

He said, “Good. But just so you know, odds are good that if you’ve got to shoot out here, you won’t be shooting at rotters. Minnericht’s got friends; or he’s got employees, anyway. Sometimes they patrol down here. This is the edge of the turf between the Chinamen’s quarters and the old transportation depot. You know how they were building a new train station, when the walls went up?”

“Yes,” she said, and then she headed him off. “I heard that Minnericht lives out there, under the half-built station.”

“Right. That’s how I heard it too.” He leaned against the door to open it another foot or two, and it opened up almost as much as it opened out. It wasn’t until it fell to the side that Briar realized she’d be climbing up from underground.

“Have you ever seen him?” she asked. “Dr. Minnericht, I mean?”

“No, ma’am,” Squiddy told her, but he didn’t look at her.

“Really? Is that so?”

He held the door for her, and she emerged up into a spot that was still underground, but with a perilous canopy of broken street looming over their heads. The afternoon drizzle of sun cut around its edges to illuminate the pit.

He said, “Yeah, that’s so. Why wouldn’t it be?”

“It’s just that you said he gave you the helmet. And I heard you might owe him money sometimes, that’s all. I thought maybe you’d seen him. I’m just curious. I wondered what he looked like.” She figured he’d heard the rumors — it seemed everybody had — and since Squiddy didn’t know of her chats with Swakhammer and Lucy, he wouldn’t know that she’d already made up her mind about the mysterious doctor.

Her guide scrambled up behind her and let the door drop down. Once it had closed, it was all but impossible to spot; its exterior had been fixed with detritus, and when it swung out on those croaking hinges, it must’ve looked like the earth itself was opening to let them out.

Squiddy finally said, “I’ve owed him money once or twice, that’s a fact. But really I just owe his men. I used to run with them, a little. Not much,” he added fast. “I never worked for him proper-like. But I’d run an errand or two for some extra food or whiskey.”

He stood beside the door and looked as if he’d like to scratch his head, if he could reach it. “When the walls first cut us off in here, we didn’t have it all figured out right away. Times was hard for a few years. Aw, times is hard now, too. I know. But it used to be you could die for breathing. It used to be, you were fighting the rotters for spoiled fruit peels and rat meat.”

“You did what you had to do. I understand.”

“Good, good. I’m glad you’re the understanding kind.” He flashed that yellow-toothed smile. “I thought you might be. You come from a fair sort of stock.”

At first she didn’t catch his meaning, but then she remembered why they’d taken her in so quickly. “Well,” she said, because she wasn’t sure what else to say. She’d spent twenty years trying to prove she wasn’t a thing like her father, and now she had his reputation to thank for her own safety in a very strange place. She wondered what he would’ve thought of it if he’d known. Privately, she suspected that he would’ve been appalled, but then, she’d been wrong about him once or twice before.

So she said, “I appreciate you saying so.” And she didn’t ask him any more questions. She’d rather listen to his silence than listen to his lies.

“Now tell me, Miss Wilkes. What are we looking for, precisely?”

“Some sign,” she said. “Of my boy, I mean. Anything at all that shows he might’ve been here.”

“Like what?”

She thought about it as she poked her way through the debris. Chunks of decaying wooden walkways hung over the edges of the shattered streets, and splinters rained down to settle on her hat. There was no wind and there was no sound. It was like standing underwater in a stagnant pond. All around them the dirty yellow air hung in place. At any moment, Briar thought, the world might freeze and she would stay there, stuck in amber.