Kate and August stood in the darkened car, gasping for breath as the shadows swarmed outside, gnashing and throwing themselves against the Plexiglas, but the walls were striped with iron, and soon the monsters shrank back into the tunneled dark. Their scent lingered, a mix of ash and damp decay.

Kate collapsed onto a bench seat. “You were right,” she said. “Worst plan ever.”

“Told you,” said August, sinking onto his knees. He examined the violin, wincing at the sight of the large scratch running down the wood. He dug around in the case until he found the pouch of new strings,and set to work by the light of Kate’s HUV beam.

“Why the violin?” she asked, her voice shaking.

August didn’t look up. “Sunai use music to bring a soul to surface,” he said, freeing the broken strings.

“I get that,” she said. “But why a violin? Can you use anything?” She drummed fingers on the subway seat. “If you made a beat, would that count as music?”

August shook his head. “Hold the light a little higher.” He hooked the first string and threaded it through the peg.

“We each have a song,” he explained. “A piece of music that belongs only to us, something we’re born with, like a fingerprint.” He tightened the string. “Leo can use almost anything to play his song—guitar, piano, flute—but Ilsa’s doesn’t work with anything except her voice. And my song only comes out right when I use this.” He plucked at the one taut string. “My sister thinks it’s about beauty. That our music correlates to the first beautiful sound we heard. I heard a violin. She heard someone singing.”

“And Leo?”

August hesitated. By Ilsa’s logic, Leo must have found beauty in everything. But he couldn’t imagine his brother seeing the world as anything but broken. Something to be fixed.

“Who knows . . .”

He worked in silence for a few moments, replacing the second and third strings.

“There’s a big difference, you know,” said Kate, “between can’t and won’t.”

“What?” He glanced over. Even in the near-black car, she looked pale.

“When you took my hand, you told me not to worry. You didn’t say you wouldn’t hurt me. You said you couldn’t.” August turned his attention back to the violin. This wasn’t the time.

“I’ve seen footage,” she continued, a strange tremor in her voice, “of Leo reaping. He touches people and takes their souls. But when you touched me, nothing happened. Why?”

August hesitated, tightening the final string. “We can only take the souls of those who’ve harmed others.”

“I’ve harmed people,” said Kate defensively, as if it were some kind of badge.

“Not like that.”

“How do you know?”

“Because your shadow doesn’t have a life of its own, and your soul doesn’t glow red.”

Kate went quiet for a few moments, then said, “What do your tallies really stand for?”

August plucked each string, tuning it by ear. “Days.”

He returned the violin to its case, and Kate turned the flashlight off, plunging them both into the pale red glow of the box lights on the tunnel walls. “Wouldn’t want it to burn out,” she whispered.

August didn’t argue. He sat on the floor across from her, his back against the seat, and rubbed the tallies on his wrist. Even lost inside the song earlier, he’d felt the latest mark, a new day, a line of heat against his skin.

“How many?” she asked.

“Four hundred and twenty-two.”

“Since what?”

He swallowed. “Since I last fell.”

“What do you mean, fell?”

“It’s what happens if Sunai stop feeding. They . . . go dark. They lose the ability to tell the difference between good and bad, monster and human. They just kill. They kill everyone. It’s not even about feeding, when that happens. It’s just . . .” he trailed off with a shudder. He didn’t say that every time Sunai went dark, they lost a piece of their souls—if they had souls—a part of what made them feel human. That every single time they fell, something didn’t get back up.

“What does it look like,” pressed Kate, “when you go dark?”

“I don’t know,” he said shortly, “I can’t exactly see myself.”

“But you said, before, that you’d rather die than let it happen again.”

No hesitation. “Yes.”

Kate’s eyes danced in the low light. “How many times has it happened, August?”

Her questions were easier to bear when he couldn’t really see her. “Twice,” he said. “Once, when I was much younger, and then . . .”

“Four hundred and twenty-two days ago,” she finished for him. “So what happened?”

August hesitated. He didn’t talk about it. He never talked about it. There was no one to talk to. Henry and Emily didn’t understand—couldn’t understand—and Leo thought the soul was a distraction, had burned it away on purpose, and Ilsa, well, the last time she went dark, she apparently took a chunk of V-City with her.

“I stopped eating,” he said at last. “I didn’t want to do it anymore. Didn’t want to feel like a monster. Henry and I got into a fight, and I stormed out. Spent most of the day wandering the city in a daze, stuck in my own head.” His eyes drifted shut as he remembered. “I was finally heading back when a fight broke out and I—you know when you’re hungry, and the smell of food is intoxicating? When you’re famished, and it’s all you can think of? I could smell the blood on their hands, and then . . .” His voice wavered. “I remember feeling so empty. Like there was a black hole inside, something I had to fill and couldn’t. No matter how many people I killed.” The words left his throat raw and his fingers shaking. “So yes, I’d rather die than face that again.”

Kate had gone quiet.

August dragged his eyes open. “What, no quip?”

She was slumped on the bench, her eyes closed, and he thought for a second she’d just nodded off, but her arm, which had been crossed over her stomach, had fallen into her lap, and it was slick with something blackish and wet.

Even in the dim car, he knew it was blood.