James twisted the handle sideways, as if turning a corkscrew. There was a loud click as the Pyxis popped open. All through the Sanctuary, the white candles spat and guttered. James sprang back, raising his blade.

There was a sound like the whistle of a train at night, and smoke billowed from the open Pyxis, bringing with it a foul, burnt smell. Cordelia coughed, raising Cortana. She heard James call out, “Barachiel!” and the light of his seraph blade cut through the smoke, followed by the blades of the others—Matthew, Christopher, and Lucie.

Something was rising through the smoke—something like a massive caterpillar, greenish in color, with a segmented, undulating body and a smooth head slashed across by a lipless mouth. The mouth cracked open, showing row upon row of blackened teeth. Then, to Cordelia’s surprise, it spoke.

“At last I am free,” it hissed. “I, Agaliarept, am free to recover the domain of my master, stolen from him by a demon of great cunning. I shall retrieve his lost world and flood this one with blood and death.” Its blind head turned toward the Shadowhunters. “Those who have freed me, what is thy bidding? Speak! I am commanded to do anything you ask.”

“Anything?” said Matthew curiously.

There was a flash of light as James’s seraph blade arced through the smoke and plunged into the demon’s middle. Black ichor sprayed as the demon shrieked in a high, chittering voice. The candles guttered and went out as James pulled his blade free; he was spattered with black fluid, his jaw set, his eyes glittering.

The demon howled and vanished, leaving only smoke and stink behind. Lucie staggered back, coughing, her face screwed up in disgust.

“But it would have done our bidding!” Matthew protested.

“It seemed untrustworthy,” said James, wiping ichor from his face with his sleeve. His seraph blade had gone dark.

“I thought he seemed all right, for a demon,” said Christopher. “You know.”

“What is going on here?” said a loud voice.

They all spun around, Cordelia raising Cortana reflexively. She waved smoke away from her face and stared.

Someone had come in through the door to the street outside. A tall man—very tall, with a shock of black hair. His skin was brown, a shade darker than Cordelia’s own, his eyes gold-green and slit-pupilled like a cat’s. He was dressed as if for a summer wedding, in a gray frock coat and trousers, with gray suede gloves and boots. The outfit was topped off by a magnificent waistcoat of gray-and-magenta brocade, a walking stick, and bright magenta spats.

“Magnus Bane?” said Matthew, with a mixture of amazement and horror.

Magnus Bane walked some distance into the Sanctuary, shaking his head as he studied the scene before him. “I want to know what you’re doing, but I must confess I’m afraid to find out,” he said. “A spot of demon-summoning, I gather?”