Up ahead, the tunnel opened onto another cavernous space. A shape glinted in the middle. Not eyes, or teeth, but the metal corners of a train car.

Something scratched the walls of the tunnel at Kate’s back, the skritch skritch cutting through August’s faltering song. She didn’t turn. She wouldn’t turn. Seeing wouldn’t help. It would only make it real.

“Kate,” said August, right before the third string broke.

“Yeah?”

“Run.”

They ran.

As fast as they could, the last tendrils of music and light trailing behind them like streamers, dissolving too quickly into the dark. The music had kept the Corsai at bay, but they were patient, they were waiting, and as soon as the song gave way, they were on them, surging forward in a mass of claws and teeth.

August kept his eyes ahead, and Kate slashed with the flashlight, trying to keep them back as they raced for the subway car. They reached the door hand in hand moments before the first monsters reached them.

August leaped up the steps, but Kate stumbled beside him, letting out a cry before he could haul her up. He threw his arms around her, shielding her body with his own as the Corsai hit the train car in a wave of breakruinbone. They hissed and tore at the air, claws raking the steel, but they wouldn’t touch August, so they couldn’t reach Kate.

“The door!” he shouted as a creature tried to tear the violin from his hands. “Hurry!”

Kate was shaking and pale, but she twisted in his arms, curled her fingers around the door, and pulled.

The metal slid sideways with a resistant groan. They tumbled in and tried to force it closed. A Corsai’s clawed arm stretched through, but when August pressed his hand against the shadowed flesh the thing recoiled as if burned, and the door ground shut.

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.