When we finished, I closed the sheet music and inspected the cover—a lithograph of seven towering demons stomping the life out of some poor urchin. The text credited music and lyrics to “J. W. Howe,” who had written it for a forgotten Bowery spectacle of 1910 called Devils of the West Side. I set the music aside, hoping Brass wouldn’t ask me to play it a second time, and heard him choke back a sob.

He lit a cigarette. His lips were so wet, they soaked straight through the paper.

“Something in this city has it out for us,” he said. “I see it in the corners, no matter how loud the music gets, no matter how bright I turn up the lights. It’s just a flicker. They dart in from the balcony, the elevator shaft. You have to be quick to escape them, and I get a hair slower every day. Do you see the shadows move?”

“I have.”

“That’s lucky, then. If you see them, you can get out of the way. Or maybe it’s not so lucky—maybe if you see them, that means they’re coming for you, no matter what.”

“What else did my father tell you?”

“He said he’d put it all together. I didn’t think he had. What he talked about . . . it didn’t make sense. He told me all about this, this . . .”

“Shadow city.”

“A city of the dead, right here, all around us, sharing our streets and our buildings and our bedrooms, and never crossing paths. He said it had been here forever, that maybe it was what made the Westside so odd, but that the two cities never touched until 1903.”

“The vanishing of Alice Pearl.”

“That’s the name. He said he had it all sorted out.”

“How?”

“It came down to the date. She disappeared when?”

“May 15, 1903,” I said—a date I knew like my own birthday.

“Galen made his first run upriver two days earlier, with my money and his bankroll. That, your father said, that is what killed Alice Pearl. Because he wasn’t just going upriver—he was sailing into that shadow city and coming back with goods that couldn’t be gotten anywhere else. Those trips opened up some kind of tear between the two cities, and poison—that was his word, ‘poison’—flooded forth.”

“I’ve seen the shadow city. There’s nothing there but death. Nothing to sell or trade. There’s no easy way to get there and no safe way out. What was Galen doing there? How was he traveling back and forth?”