From the landing you could see that the white and black tiles that patterned the floor formed the shape of the Angel Raziel, rising from the waters of Lake Lyn in Idris, holding two of the Mortal Instruments—a flashing sword and a gold-encrusted cup.

It was an image every Shadowhunter child knew. A thousand years ago the Angel Raziel had been summoned by Jonathan Shadowhunter, the father of all Nephilim, to put down a plague of demons. Raziel had gifted Jonathan with the Mortal Instruments and the Gray Book, in which all runes were inscribed. He had also mixed his blood with human blood and given it to Jonathan and his followers to drink, allowing their skin to bear runes and creating the first of the Nephilim. The image of Raziel rising was sacred to Nephilim: It was called the Triptych and was found in places where Shadowhunters met or where they had died.

The image on the floor of the Institute’s entryway was a memorial. When Sebastian Morgenstern and his faerie army had stormed the Institute, the floor had been plain marble. After the Dark War, the Blackthorn children had returned to the Institute to find that the room where so many had died was already being torn up. The stones where Shadowhunters had bled were replaced, and the mural put in to commemorate those who had been lost.

Every time Emma walked on it, she was reminded of her parents and of Julian’s father. She didn’t mind—she didn’t want to forget.

“When you said they are and they aren’t, did you mean because Arthur was here?” Cristina asked. She was looking thoughtfully down on the Angel.

“Definitely not.” Arthur Blackthorn was the head of the Los Angeles Institute. At least, that was his title. He was a classicist, obsessed with the mythology of Greece and Rome, constantly locked in the attic with bits of old pottery, moldering books, and endless essays and monographs. Emma didn’t think she’d ever seen him take a direct interest in a Shadowhunter issue. She could count on one hand the number of times she and Cristina had seen him since Cristina’s arrival at the Institute. “Although I’m impressed you remember he lives here.”

Cristina rolled her eyes.

“Don’t roll your eyes. It punctures my dramatic moment. I want my dramatic moment unpunctured.”

“What dramatic moment?” Cristina demanded. “Why have you dragged me out here when I want to shower and change out of this gear? Besides, I need coffee.”

“You always need coffee,” said Emma, moving back toward the corridor and the other wing of the house. “It’s a debilitating addiction.”

Cristina said something uncomplimentary under her breath in Spanish, but she followed Emma nonetheless, her curiosity clearly winning out. Emma spun around so she could walk backward, like a tour guide.

“Okay, most of the family is in the south wing,” she said. “First stop, Tavvy’s room.” The door of Octavian Blackthorn’s room was already open. He wasn’t that invested in privacy, being only seven. Emma leaned in, and Cristina, looking puzzled, leaned in beside her.

The room contained a small bed with a brightly striped coverlet, a playhouse nearly as tall as Emma, and a tent full of books and toys. “Tavvy has nightmares,” Emma said. “Sometimes Julian comes and sleeps in the tent with him.”

Cristina smiled. “Di—my mother used to do that for me when I was a little girl.”

The next room was Drusilla’s. Dru was thirteen and obsessed with horror movies. Books about slasher films and serial killers littered the floor. The walls were black, and vintage horror posters were pasted up over the windows. “Dru loves horror movies,” said Emma. “Anything with the word ‘blood’ or ‘terror’ or ‘prom’ in it. Why do they call it a prom, I wonder—”

“It’s short for ‘promenade,’” said Cristina.

“Why do you speak English so much better than I do?”

“That wasn’t English,” Cristina pointed out, as Emma darted farther down the hall. “That was French.”

“The twins have rooms across from each other.” Emma gestured at two closed doors. “This is Livvy.” She swung a door open to reveal a beautifully clean and decorated bedroom. Someone had artfully covered the headboard with whimsical fabric decorated with a pattern of teacups. Bright costume jewelry hung from screens nailed to the wall. Books about computers and programming languages were stacked in careful rows by her bed.

“Programming languages,” Cristina exclaimed. “Does she like computers?”

“She and Ty,” said Emma. “Ty likes computers, he likes the way they organize patterns so that he can analyze them, but he’s actually not great at math. Livvy does the math and they tag team.”

The next room was Ty’s. “Tiberius Nero Blackthorn,” said Emma. “I think his parents may have gone a little overboard with the name. It’s like naming someone Magnificent Bastard.”

Cristina giggled. Ty’s room was neat, with books lined up not in alphabetical order but by color. Colors that Ty liked the most, like blue and gold and green, were at the front of the room and near the bed. Colors he didn’t like—orange and purple—were relegated to nooks and spaces by the window. It might have looked haphazard to someone else, but Emma knew that Ty was aware of the location of every volume.

On the bedside table were his most beloved books: Arthur Conan Doyle’s Sherlock Holmes stories. Beside them were a collection of small toys. Julian had made them for Ty years before when he found that having something in his hand calmed Ty down and helped him focus. There was a squiggly ball of pipe cleaners, and a black plastic cube made up of clicking parts that could be twisted into different patterns.

Cristina cast a look at Emma’s wry-fond expression and said, “You’ve talked about Tiberius before. He’s the one who loves animals.”

Emma nodded. “He’s always outside, bothering lizards and squirrels.” She waved her arm to indicate the desert that spread out behind the Institute—unspoiled land, without houses or human occupation, that stretched to the ridge of mountains that separated the beach from the Valley. “Hopefully he’s having fun in England, collecting tadpoles and frogs and toads-in-the-hole. . . .”

“That’s a kind of food!”

“Can’t be,” Emma said, moving down the hall.

“It’s pudding!” Cristina objected as Emma found the next door and opened it. The room inside was painted almost the exact same blue as the sea and sky outside. During the day it looked as if it were part of them, floating in a blue forever. Murals covered the walls— intricate patterns, and along the whole wall that faced the desert, the outline of a castle wrapped by a high wall of thorns. A prince rode toward it, his head down, his sword broken.

“La Bella Durmiente,” said Cristina. Sleeping Beauty. “But I did not remember it being so sad, or the prince so defeated.” She glanced at Emma. “Is he a sorrowful boy, Julian?”

“No,” Emma said, only half paying attention. She hadn’t come into Jules’s room since he’d gone. It looked like he hadn’t cleaned up before he left, and there were clothes on the floor, half-done sketches scattered over the desk, even a mug on the nightstand that probably held coffee that had long since molded. “Not depressed or anything like that.”