Thomas set down the book he’d been holding; Cordelia was startled to see it was a book of Sufi poetry, the verses of Hafiz and Ibn al-Farid, written out in Persian and Arabic. “Cordelia,” he said. He sounded weary, as if his voice had been slowed by grief. “Lucie. I’m glad to see you.”

“Welcome to our sanctum, ladies,” said Matthew, unscrewing the cap of his flask. “Christopher salvaged quite a bit of this furniture for us. Like King Arthur and his knights, we prefer to sit at a round table that we all might be equal.”

“Also,” Christopher added, taking a book down from the shelves and handing it to James, “it was the only table my mother was willing to spare.”

“I couldn’t go to Idris,” Thomas said rather suddenly, as if someone had demanded of him why he was still in London. “I wish to see Eugenia, but I need to stay here. I need to help Kit find the cure for this demon disease or poison or whatever this is. What happened to my sister cannot happen to someone else.”

“Sometimes grief and worry must take the form of action,” said Cordelia. “Sometimes it is unbearable to sit and wait.”

Thomas shot her a grateful look. “Exactly that,” he said. “So—Christopher told you all about the shards?”

“Yes,” Christopher interjected, “and James realized the shards are from a Pyxis.”

“A Pyxis?” Thomas echoed. “But they were destroyed after the Clockwork War. They’re unsafe—remember what happened at school.”

“Most Pyxides were destroyed after the Clockwork War,” said James. “In Gast’s flat, though, I found a drawing. It looked rather like a sketch of an ordinary box—he wasn’t a very good artist—”

“Ah, the drawing with the wobbly runes around it?” Matthew said.

“They weren’t runes,” James said. “They were alchemical symbols—the kind you’d carve onto a Pyxis box.”

“Oh!” said Lucie. “The markings on the shards. They were alchemical symbols too. Of course.”

“That wasn’t all,” said James. “On the paper Gast had scrawled a word in Old Persian. Cordelia was able to translate it.”

He looked at her expectantly.

“It was a demon’s name,” Cordelia said. “Merthykhuwar.” She frowned. Such demons had featured in old stories from her childhood; she had always thought of them as near-mythical, like dragons. “In modern Persian it would be Mardykhor. But Shadowhunters—Shadowhunters call it a Mandikhor. They are said to be viciously poisonous.”

“You think Gast summoned up a Mandikhor demon?” Matthew asked. “But aren’t they meant to be extinct? And what’ve they got to do with Pyxis boxes?”