“The good news,” she said, gripping the light, “is that I don’t think they’re going to tell Sloan we’re here.”

“And the bad news?” asked August, tucking the violin under his chin.

Kate swung the flashlight in an arc, and there was a flutter, like wings, as the Corsai parted and reformed. “The bad news,” she said, “is I don’t think they’re very happy to see us.”

She slashed again, and the beam must have finally connected with a creature’s head, because a single shadow screamed and toppled forward from the mass, white eyes winking out, teeth raining down on the damp floor like loose stones.

“Any time now,” snapped Kate as the Corsai rattled and hissed.

“Can’t rush art,” said August as he rested the bow on the strings. The darkness barreled toward them like a train, edges raking the air, but just as Kate faltered and took a step back, he finally began to play.

A single, resonant note swept through the tunnel, and everything stopped.

Sound vibrated through the air as he drew a second sound, and then a third, the chords fusing together as they formed. The music was like a blade, knifing through the dark. The melody sang through her head, and the Corsai arced back as one, as if repelled by a single, massive beam. They hissed like steam, and broke apart, and fell away beneath the music, and Kate could feel her thoughts begin to fall, too, her head swimming with the notes the way it had at Colton.

Now, in the darkness, she could see the music, too. It threaded through the air like wisps of sunlight, ribbons of color that twisted and swirled and held the shadows at bay. She reeled, suddenly dizzy, and her feet dragged to a stop. She couldn’t move, couldn’t look away. Her senses tangled in the chords as the song filled her head, swallowed her sight.

And then she looked down and saw that she was glowing, too, a strange pale light rising to the surface of her skin. She marveled at it, at the way it moved when she did, danced like steam, even though it was beneath the surface. It was like silver and smoke, pulsing faintly in time with her heart.

Was this her life?

Was this her soul?

In the distance, August’s voice reached her, soft and fluid and woven through the music. “Come on, Kate.”

The music faltered, fell away, leaving only the echoes as he reached for her arm, and in that moment she found enough sense to be afraid.

“Don’t,” she said, trying to pull away before he could steal her soul. She was too slow, but when his fingers closed around her wrist, nothing happened.

“It’s okay,” he said, his voice careful, taut. “I can’t hurt you. . . .” She looked down at the place where his skin met hers, the way the silver light seemed to bend around his fingers like a stream around a stone.

“But you need to stay close.” He drew her hand to the edge of his coat and picked up the song before the last tendrils of music could fade from the air. “Follow me.”

And the truth was, Kate probably would have followed him right over a cliff, as long as he kept playing. The words left his mouth and tangled with the music and became real, became truth. The two of them moved through the tunnel, the shifting center in a sphere of melody and light. Kate’s mind sank. She tried to swim to the surface but it kept stretching out of reach. It was like the cusp between waking and sleep, where you couldn’t hold on to your thoughts. Couldn’t hold on to anything.

But she held on to him.

The darkness thinned as they reached a station, the tunnel unfolding into an arched ceiling, a set of platforms. Tiles glittered like teeth as the light from August’s song reflected off them.

CASTER WAY, the sign flickered in the ghostly glow. They were heading northeast.

The subway tunnels thinned and opened and thinned again as tracks merged and diverged and merged again. They passed a depot of darkened cars disabled until the morning shift.

Kate wasn’t sure how long the song lasted. She couldn’t hold on to the minutes, felt herself say something, felt her mouth forming words, felt them spill out over her lips, but she couldn’t hear her own voice, only the music, and if August heard her, he didn’t respond, didn’t turn. He kept his head forward, violin up, and hands moving.

This wasn’t the boy from the bleachers or the one folded in on himself in her car. This wasn’t the one coughing black blood onto the pavement or tied to the half-constructed wall.

This was a different August Flynn.

Confident.

Mesmerizing.

And Kate felt her lips forming those words, too, but she was cut off by a sharp twang as one of the violin strings broke. August faltered, his face flashing with panic. He started up again, and the melody returned, still entrancing, but there was something . . . thinner about it. Fewer threads of light wove around them, and as the glow caught August’s face she saw a line of worry.

And then, too soon, a second string broke. August caught his breath. Now the sound was noticeably weaker. She felt its presence retreating from her mind and had a feeling that was a bad sign.

“August,” she said, an edge of warning in her voice.

“I never play this long,” he explained, eyes narrowed in focus. “My song needs all four strings.”

She could see the strain on the final two, the place where the bow met the string pricking with light, like heat. The threads in the air were starting to dim, and the darkness—and the things that writhed inside—began to press forward.