“Glamours that aren’t made by Shadowhunters,” said Livvy.

“Glamours that aren’t meant for Shadowhunters to see through,” said Kit.

Ty looked thoughtful. There was an opaqueness to him sometimes that made it hard for Kit to tell whether Ty agreed with him or not. He did, however, put his stele to the door and begin to draw the Open rune.

It wasn’t the lock that clicked, but the hinges that popped open. They jumped out of the way as the door half-fell, half-sagged to the side, slamming into the wall with an echoing sound.

“Don’t press down so hard when you draw,” Livvy said to Ty. He shrugged.

The space beyond the door was dark enough for the twins to need to spark up their witchlights. The glow of them had a pearlescent whitish tint that Kit found strangely beautiful.

They were in an old hallway, filled with dust and the webs of scuttling spiders. Ty went ahead of Kit and Livvy behind him; he suspected they were protecting him, and resented it, but knew that they wouldn’t understand his protest if he lodged one.

They went down the hall and up a long, narrow staircase, at the end of which was the rotted remains of a door. Through that door was a massive room with a hanging chandelier.

“Probably a ballroom,” Livvy said, her voice echoing oddly in the space. “Look, this part of the house is better taken care of.”

It was. The ballroom was empty but clean, and as they moved through other rooms, they found furniture shrouded in drop cloths, windows boarded carefully to protect the glass, boxes stacked in the halls. Inside the boxes were cloths and the strong smell of mothballs. Livvy coughed and waved a hand in front of her face.

“There’s got to be a library,” Ty said. “Somewhere they would keep family documents.”

“I can’t believe our dad might have visited here when he was growing up.” Livvy led the way down the hall, her body casting an elongated shadow. Long hair, long legs, shimmering witchlight in her hand.

“He didn’t live here?” Kit asked.

Livvy shook her head. “Grew up in Cornwall, not London. But he went to school in Idris.”

Idris. Kit had read more about Idris in the London Institute library. The fabled homeland of Shadowhunters, a place of green forests and high mountains, icy-cold lakes and a city of glass towers. He had to admit that the part of him that loved fantasy movies and Lord of the Rings yearned to see it.

He told that part of himself to be quiet. Idris was Shadowhunter business, and he hadn’t yet decided he wanted to be a Shadowhunter. In fact, he was quite—nearly totally—sure he didn’t.

“Library,” Ty said. It occurred to Kit that Ty never used five words when one would do. He was standing in front of the door to a hexagonal room, the walls beside him hung with paintings of ships. Some were cocked at odd angles as if they were plunging up or down waves.

The library walls were painted dark blue, the only art in the room a marble statue of a man’s head and shoulders sitting atop a stone column. There was a massive desk with multiple drawers that turned out to be disappointingly empty. Forays behind the bookshelves and under the rug also turned up nothing but dust balls.

“Maybe we should try another room,” Kit said, emerging from under an escritoire with dust in his blond hair.

Ty shook his head, looking frustrated. “There’s something in here. I have a feeling.”

Kit wasn’t sure Sherlock Holmes operated on feelings, but he didn’t say anything, just straightened up. As he did, he caught sight of a piece of paper sticking out of the edge of the small writing desk. He pulled at it, and it came away.

It was old paper, worn almost to transparency. Kit blinked. On it was written his name—not his name, but his last name, Herondale, over and over, entwined with another name, so that the two words formed looping patterns.

The other word was Blackthorn.

A deep sense of unease shot through him. He tucked the paper quickly into his jeans pocket just as Ty said, “Move, Kit. I want to get a closer look at that bust.”

To Kit, bust only meant one thing, but since the only breasts in the room belonged to Ty’s sister, he stepped aside with alacrity. Ty strode over to the small statue on the marble column. He’d pulled his hood down, and his hair stood up around his head, soft as the downy feathers of a black swan.

Ty touched a small placard below the carving. “?‘The difficulty is not so great to die for a friend, as to find a friend worth dying for,’?” he said.

“Homer,” said Livvy. Whatever kind of education the Shadowhunters got, Kit had to admit, it was thorough.

“Apparently,” said Ty, pulling a dagger out of his belt. A second later he’d driven the blade into the carved eye socket of the statue. Livvy yelped.

“Ty, what—?”

Her brother yanked the blade back out and repeated the action on the statue’s second eye socket. This time something round and glimmering popped out of the hole in the plaster with an audible crack. Ty caught it in his left hand.

He grinned, and the grin changed his face completely. Ty when he was still and expressionless had an intensity that fascinated Kit; when he was smiling, he was extraordinary.

“What did you find?” Livvy darted across the room and they gathered around Tiberius, who was holding out a many-faceted crystal, the size of a child’s hand. “And how’d you know it was in there?”

“When you said Homer’s name,” said Ty, “I recalled that he was blind. He’s almost always depicted with his eyes shut or with a cloth blindfold. But this statue had open eyes. I looked a little closer and saw that the bust was marble but the eyes were plaster. After that, it was . . .”

“Elementary?” said Kit.

“You know, Holmes never says, ‘Elementary, my dear Watson,’ in the books,” said Ty.

“I swear I’ve seen it in the movies,” Kit said. “Or maybe on TV.”

“Who would ever want movies or TV when there are books?” said Ty with disdain.

“Could someone here pay attention?” Livvy demanded, her ponytail swinging in exasperation. “What is that thing you found, Ty?”

“An aletheia crystal.” He held it up so that it caught the glow of his sister’s witchlight. “Look.”

Kit glanced at the faceted surface of the stone. To his surprise, a face flashed across it, like an image seen in a dream—a woman’s face, clouded around with long dark hair.

“Oh!” Livvy clapped her hand over her mouth. “She looks a little like me. But how—?”

“An aletheia crystal is a way of capturing or transporting memories. I think this one is of Annabel,” said Ty.

“Aletheia is Greek,” Livvy said.

“She was the Greek goddess of truth,” said Kit. He shrugged when they stared at him. “Ninth-grade book report.”

Ty’s mouth crooked at the corner. “Very good, Watson.”

“Don’t call me Watson,” said Kit.

Ty ignored this. “We need to figure out how to access what’s trapped in this crystal,” he said. “As quickly as possible. It could help Julian and Emma.”

“You don’t know how to get into it?” Kit asked.

Ty shook his head, clearly disgruntled. “It’s not Shadowhunter magic. We don’t learn other kinds. It’s forbidden.”

This struck Kit as a stupid rule. How were you ever supposed to know how your enemies operated if you made it forbidden to learn about them?

“We should go,” Livvy said, hovering in the doorway. “It’s starting to get dark. Demon time.”

Kit glanced toward the window. The sky was darkening, the stain of twilight spreading across the blue. The shadows were coming down over London.

“I have an idea,” he said. “Why don’t we take it to the Shadow Market here? I know my way around the Market. I can find a warlock or even a witch to help us get at whatever’s in this thing.”

The twins glanced at each other. Both were clearly hesitant. “We’re not really supposed to go to Shadow Markets,” said Livvy.

“So tell them I ran off there and you had to catch me,” said Kit. “If you even ever have to explain, which you won’t.”