“Then he’s found it,” Emma said. “Caul wouldn’t have pulled the trigger and kidnapped the ymbrynes if he didn’t know where Abaton was.”

“I thought you said it was legendary,” I said. “Now you’re talking like it’s a real. Which is it?”

“The official position of the Council of Ymbrynes is that the Library of Souls is nothing but a story,” Bentham said.

“I don’t care what the council says,” said Emma. “What do you say?”

“My opinions are my own,” he said evasively. “But if the library is real, and Jack manages to find and open it, he still won’t be able to steal its souls. He doesn’t know it, but there’s a third element he needs, a third key.”

“And what’s that?” I said.

“No one can take the soul jars. To most everyone they would be invisible and intangible. Even ymbrynes can’t touch them. In the stories, only special adepts called librarians can see and handle them—and a librarian hasn’t been born for a thousand years. If the library exists, all Jack would find there are empty shelves.”

“Well, that’s a relief,” I said.

“Yes and no,” said Emma. “What’s he going to do when he figures out the ymbrynes he spent so long hunting are useless to him? He’ll go mad!”

“That’s what I worry about most,” Bentham said. “Jack has a bad temper, and when the dream he’s nurtured for so long dies …”

I tried to imagine what that could mean—all the tortures a man like Caul might be capable of—but my mind recoiled from the idea. It seemed the same horrors had broadcast themselves to Emma, because what she said next was sharp and charged with anger.

“We’re going to get them back.”

“We share a common goal,” Bentham said. “To destroy my brother and his kind, and to save my sister and hers. Together, I believe we can do both.”

He looked so small in that moment, sunk into the massive couch, cane leaning against his rickety legs, that I nearly laughed.

“How?” I said. “We’d need an army.”

“Incorrect,” he replied. “The wights could easily repel an army. Luckily, we have something even better.” He looked at Emma and me, his lips curling into a smile. “We have the both of you. And luckily for you, you have me.” Bentham leaned on his cane and rose slowly to his feet. “We have to get you inside their fortress.”

“It seems pretty impenetrable,” I said.

“That’s because it is, conventionally speaking,” Bentham replied. “In the years when Devil’s Acre was a prison loop, it was designed to hold the worst of the worst. After the wights returned here, they adopted it as their home—and what had been an inescapable prison became their impenetrable fortress.”

“But you have a way in,” Emma guessed.

“I might, if you can help me,” Bentham said. “When Jack and his wights came, they stole the heart of my Panloopticon. They forced me to break my own machine, to copy its loops and re-create them inside their fortress so that they could continue their work in a more protected location.”

“So there’s … another one?” I said.

Bentham nodded. “Mine is the original and theirs is the copy,” he said. “The two are linked, and there are doorways in each that lead to the other.”

Emma sat up straight. “You mean, we can use your machine to get inside theirs?”

“Correct.”

“Then why haven’t you?” I said. “Why didn’t you do it years ago?”

“Jack broke my machine so irrevocably that I thought it could never be fixed,” Bentham said. “For years, only one room has remained functional: the one that leads to Siberia. But though we’ve searched and searched, we haven’t found a way through it into Jack’s machine.”

I remembered the man we’d seen peering into the crevasse—looking for a door, it seemed, deep in the snow.

“We need to open other doors, other rooms,” Bentham said, “but to do that I need an adequate replacement for the part Jack stole—the dynamo at the heart of my Panloopticon. I’ve long suspected there’s something that might work—a very powerful, very dangerous item—but though it exists right here in Devil’s Acre, getting one has never been possible for me. Until now.”

He turned to me.

“My boy, I need you to bring me a hollowgast.”

* * *

I agreed to, of course. I would’ve said yes to almost anything then if I thought it might help free our friends. It occurred to me only after I’d said it, though, and Bentham had clapped his hands around mine and shook them, that I had no idea where to get a hollowgast. I was sure there were plenty inside the wights’ fortress, but we’d already established that there was no getting inside. That’s when Sharon stepped out of the shadows that had been growing at the edges of the room to give us a bit of good news.

“Remember your friend who got smashed by a falling bridge?” he said. “Turns out he’s not quite dead. They pulled him out of the Ditch a few hours ago.”

“They?” I said.

“The pirates. They’ve got him chained and caged down the end of Oozing Street. He’s causing quite a stir, I hear.”

“That’s it, then,” Emma said, tensing with excitement. “We’ll steal the hollow and bring him back here, restart Mr. Bentham’s machine, open a door to the wights’ fortress, and get our friends back.”