“Hypatia’s here?” Lucie looked puzzled. “But how—?”

They had reached a part of the Market where caravans were set up in a loose circle. In the center of the circle a bonfire of enchanted flames burned: as the sparks rose up, they took on different shapes—roses, stars, towers, crescent moons, even a coach-and-four. Ahead of them, freshly painted in purple and gold, was a caravan with an elaborately lettered advertisement on the side for Hypatia Vex’s new magic shop in Limehouse.

“Can we trust Hypatia?” said James. “She does seem to like Anna, but I’m not sure how far that liking stretches where we’re concerned. Especially since we stole her Pyxis.”

“She did mention that when Cordelia and I were at the Ruelle,” said Matthew, shooting Cordelia a rueful look. “She seemed to have come to terms with it. And she likes me.”

“Does she?” said Cordelia. “I really couldn’t tell.”

“Shadowhunters!” called a voice, rising above the noise of the Market. Cordelia turned to see Magnus Bane standing in the doorway of the purple-and-gold caravan. He wore a fitted silver frock coat, brilliant peacock-blue trousers, and a matching embroidered waistcoat, with a watch on a glittering chain tucked into one pocket. Silver cuff links glittered at his wrists, and he wore a silver ring set with a luminous blue stone. “What on earth are you doing, wandering around the Shadow Market like chickens waiting to get your heads cut off? Come inside immediately.”

He shooed them in, shaking his head as they spilled into the caravan. Inside, Hypatia had left her mark on every surface: jewel-toned velvet cushions were piled on the fringed carpets; gilded mirrors and exquisitely framed Japanese illustrations lined the walls. Lamps glowed from coved niches, and in the center of the room was a small table covered in papers—scribblings about the Limehouse magic shop, from what Cordelia could see.

“Magnus!” Lucie said, delighted, as she and the others found places on the scattered cushions. It was delicious to be in the warmth after the icy night outside. Cordelia sank into a massive blue velvet cushion, wiggling her toes inside her boots as they began to thaw. James settled beside her, his shoulder warm against her side. “Are you and Uncle Jem back, then? From the Spiral Labyrinth?”

“I’m only in London for tonight,” Magnus explained, settling into a brightly painted rattan chair. “Hypatia has kindly allowed me to hole up here, as my flat is full of ice trolls. It’s a bit of a long story. Brother Zachariah, alas, is still in the Labyrinth. His work ethic is unimpeachable.”

Cordelia cast a sideways glance at James. Did it bother him that Jem was so out of reach? If so, she could not tell; his expression was unreadable.

“Perhaps my information is out of date,” Magnus went on, setting out a tray laden with small dishes of biscuits, nuts, and sugary jellies. “But isn’t there a murderer on the loose in London? Should you lot really be out on your own? Not to mention the Shadow Market isn’t that welcoming of Nephilim.”

“Dealing with monsters is what we do,” James said, reaching for a biscuit. “It’s our job.”

“And all the murders have happened in the early morning,” Cordelia said. “So it doesn’t follow that it’s not safe in the evening.”

“Besides, the killer wouldn’t dare strike here, not with so many Downworlders around. The murders have been happening in the shadows, on deserted streets,” said Christopher. “Drawing from a sample set of five, the logical conclusion—”

“Oh dear, not logic, please.” Magnus held his hands up in a conciliatory fashion. “Well, you certainly aren’t the first generation of young Nephilim to decide saving the world is your responsibility,” he said. “But what are you doing in the Market?”

James hesitated only a moment before taking the pithos out of his coat pocket and handing it to Magnus. He explained as quickly as he could the situation: Thomas mistaking it for a stele, James taking the object before the Inquisitor arrived, their suspicion that it might have something to do with the murders, Christopher giving it its name.

“I am not sure your friend Thomas was as mistaken as he thought,” said Magnus. He pressed down on a particular rune with a well-manicured finger. With a faint click, the box elongated and rearranged itself into a new, familiar shape.

“It is a stele,” Christopher said in amazement, leaning in close to stare.

“It is certainly modeled on one,” said Magnus. “And I would say this was Shadowhunter work, but … all magic has a kind of alliance. The tools of the Nephilim are angelic. Adamas itself has a seraphic alliance, while objects from the realms of demons are demonic in their very nature. This”—he nodded at the object in his hand—“is demonic. And the runes bear a resemblance to the runes of the Gray Book, but they have been altered. Changed. Rendered in a demonic script. A demonic demotic, if you will.” He wiggled his eyebrows. “All right, no one got that joke. Over your heads, I suppose. The point is, this is a demonic artifact.”

“Might I examine it again?” Christopher asked.

Magnus handed it over, his eyes betraying a flicker of concern. “Just be careful. It’s certainly not a toy.”

“An Iron Sister couldn’t have made it?” asked Matthew. “Gone a bit barmy on the crumpet in the Adamant Citadel and started up production of evil objects?”

“Certainly not,” said Lucie. “The Iron Sisters take their job very seriously, and even if they didn’t, you can’t make demonic objects in the Adamant Citadel. The wards won’t let you. I used to want to be an Iron Sister,” she added, as everyone looked at her in surprise, “until I found out how cold it gets in Iceland. Brr.”

“Could someone else have taken a stele and reversed its alliance?” James asked. “Made it demonic?”

“No,” said Magnus. “It was never a real stele. It was made the way you see it now, I’m sure of it. Very unlikely to have been Lilian Highsmith’s. I would agree—that object belongs to whoever has been committing these murders.”

“Could a demon shape adamas?” said James. “We believe a demon is connected to these murders somehow. Not perhaps that he is committing the murders, but that his—will—is somehow involved.”

“No idea which demon?” Magnus asked casually, selecting a biscuit from the platter.

James exchanged a quick look with the rest of the group. Matthew shrugged and nodded, speaking for them all: it was James’s secret to tell.

“Belial,” James said. “Somehow, he seems to have regained enough strength, even after his wound, to return to me in dreams. I have been having … visions, it seems, of the murders. I see them happen. I almost feel as if I’m the one—the one doing the killing.”

“You feel as if you’re the one … ?” Magnus narrowed his cat’s eyes. “Would you care to elaborate?”

“James is definitely not committing the murders,” Cordelia said hotly. “Do you think we’d be foolish enough not to think of that? We tested him—he’s innocent.”

“They tied me to a bed,” James said, examining a piece of Turkish delight.