“Magnus said the Princes had alliances,” said Cordelia slowly. “Azazel and Asmodeus. Belial and—”

“Leviathan,” said Matthew, who had gone a little white around the mouth. “James, you said the sigils can function as gates. If this murder happens—it will open up a gate for Leviathan to enter our world?”

“Do you think it’s already happened?” Cordelia asked.

James glanced at the window. “No. In my vision it was just after dawn, and dawn is breaking now. Mount Street Gardens isn’t far, but we have no time to waste. We must run—”

“Not like that, you’re not,” said Matthew sternly. “You need shoes, weapons, and a gear jacket at least. And Cordelia needs boots.”

“And then?” said Cordelia.

“Then we run.”

As Thomas barreled through the Institute and into the entryway, he heard someone calling his name. Everything was chaos, a seething mass of Shadowhunters surging to and fro, catching up weapons, throwing on gear, and charging out the open front doors into the courtyard beyond, from which the sounds of fighting were already audible.

“Thomas! Here!” It was Christopher, pushing toward him through the crowd; he was holding a gear jacket and a number of seraph blades. “Where’s Uncle Will?”

“Went to find Tessa.” Thomas took the jacket and threw it on, jamming some of the blades into his belt. “What’s happening?”

“Some kind of attack. Your parents are out there already, joined the fighting. Mine, too—well, Father has. Mother’s upstairs with Alexander. But the Institute’s not safe. Do you want some seraph blades?”

Thomas was about to protest that he’d already taken several when he realized Christopher wasn’t talking to him. He was talking to Alastair, who seemed to have remained at Thomas’s side. Thomas determined to analyze this development at a later date.

Alastair nodded his thanks and took the weapons. He headed to the front doors while Thomas was still fastening his jacket. Christopher followed—he was saying something about the adamas object Thomas had found, and about Matthew having run to get James. His voice trailed off as he joined Thomas and Alastair at the front door.

The courtyard was in ruins. A massive black cloud hid the Institute and its surroundings in shadow: bright beams of witchlight lanced back and forth across the courtyard, illuminating scenes of battle—there was Gideon, sword in hand, climbing atop a pile of rubble. Anna, in gear, back-to-back with Ariadne, her whip tracing a thin gold line across the air.

“But what are they fighting?” said Alastair—for once voicing what everyone was thinking. “It’s too bloody dark to see, and—” He wrinkled his nose. “It smells of fish.”