“Here.” Matthew reached out; James caught hold of his parabatai’s hand and hauled himself upright. He still felt dizzy, and somehow different—lighter, though he could not begin to explain why. He leaned back against the marble fireplace, catching his breath, Matthew’s worried gaze fixed on him. “Steady on, Jamie bach.”

James realized three things simultaneously. One was that he’d been kissing Cordelia what felt like moments ago, but no evidence of their embrace remained: Cordelia wore a gear jacket buttoned over her dress, and a watchful expression. He himself was wearing a clean shirt, which seemed an even greater mystery.

The second was that Matthew must have just arrived: he hadn’t yet taken off his bright green brocade-and-velvet overcoat, and one end of his long ivory scarf trailed on the floor.

The third was that it was as if someone had unlatched a cage inside him, letting his mind run free. He very urgently needed several things at once: an answer, a map, and a book. “Math,” he said. “The pithos—did Christopher lose it?”

Matthew’s eyes widened. “It was stolen—by someone who looked like me. How did you know it was gone?”

“Because he has it,” James said. “Belial. He must have sent an Eidolon demon to Christopher, to trick him.” He took a deep breath. “I think—I think I may know what’s happening.”

Cordelia rose to her feet, Cortana gleaming where it was strapped to her back. She blushed a little as she looked at him. “What do you mean, you know? You know who’s responsible for the murders?” she demanded. “I mean, Belial, of course—”

“I don’t know all of it,” said James, racing to the center table, where books on dreams and magic still lay scattered haphazardly. “But some of it. Why he’s doing what he’s doing. Maybe even how. Here—” He yanked the dark purple volume free. “The map,” he said. “That map of London—where is it?”

“Here.” Matthew slid the book toward him, open to the map in the center. Hurriedly James glanced at the Monarchia, then back at the map. He picked up a pen and made one last mark.

“Mount Street Gardens?” said Matthew, squinting at the new scrawl. “We’ve been there before. It’s quite near here.”

“But that still doesn’t make Belial’s sigil, does it?” said Cordelia, glancing over Matthew’s shoulder. “It looks rather like Poseidon’s trident. A sort of spear with three prongs.”

“It is a sigil,” said James. “Just not Belial’s. It’s Leviathan’s sigil.” He tapped the Monarchia, where Leviathan’s sigil was scrawled across a full page, spiky and vicious-looking. “Thus the trident. He is a sea demon, after all.”

Matthew and Cordelia exchanged a puzzled look. This was it, James thought; they were going to declare him mad and toss him in the attic.