“Emma?” Julian leaned forward, and everything seemed to explode around them. There was a sudden enormous flash of light, and the world outside the windows turned white-gold and red, as if the Institute had caught on fire. At the same time the floor under them rocked like the deck of a ship. Emma slid forward just as a terrible screaming rose from downstairs—a horrible unrecognizable scream.

Livvy gasped and went for Ty, wrapped her arms around him as if she could encircle and protect his body with her own. Livvy was one of the very few people Ty didn’t mind touching him; he stood with his eyes wide, one of his hands caught in the sleeve of his sister’s shirt. Mark had risen to his feet already; Katerina was pale under her coils of dark hair.

“You stay here,” she said to Emma and Julian, drawing her sword from the sheath at her waist. “Watch the twins. Mark, come with me.”

“No!” Julian said, scrambling to his feet. “Mark—”

“I’ll be fine, Jules,” Mark said with a reassuring smile; he already had a dagger in each hand. He was quick and fast with knives, his aim unerring. “Stay with Emma,” he said, nodding toward both of them, and then he vanished after Katerina, the door of the training room shutting behind them.

Jules edged closer to Emma, slipped his hand into hers, and helped her to her feet; she wanted to point out to him that she was just fine and could stand on her own, but she let it go. She understood the urge to feel as if you were doing something, anything to help. Another scream suddenly rose from downstairs; there was the sound of glass shattering. Emma hurried across the room toward the twins; they were deadly still, like little statues. Livvy was ashen; Ty was clutching her shirt with a death grip.

“It’s going to be okay,” Jules said, putting his hand between his brother’s thin shoulder blades. “Whatever it is—”

“You have no idea what it is,” Ty said in a clipped voice. “You can’t say it’s going to be okay. You don’t know.”

There was another noise then. It was worse than the sound of a scream. It was a terrible howl, feral and vicious. Werewolves? Emma thought with bewilderment, but she’d heard a werewolf’s cry before; this was something much darker and crueler.

Livvy huddled against Ty’s shoulder. He raised his little white face, his eyes tracking from Emma to rest on Julian. “If we hide here,” Ty said, “and whatever it is finds us, and they hurt our sister, then it’s your fault.”

Livvy’s face was hidden against Ty; he had spoken softly, but Emma had no doubt he meant it. For all Ty’s frightening intellect, for all his strangeness and indifference to other people, he was inseparable from his twin. If Livvy was sick, Ty slept at the foot of her bed; if she got a scratch, he panicked, and it was the same the other way around.

Emma saw the conflicting emotions chase themselves across Julian’s face—his eyes sought hers, and she nodded minutely. The idea of staying in the training room and waiting for whatever had made that sound to come to them made her skin feel as if it were peeling off her bones.

Julian strode across the room and then returned with a recurve crossbow and two daggers. “You have to let go of Livvy now, Ty,” he said, and after a moment the twins separated. Jules handed Livvy a dagger and offered the other one to Tiberius, who stared at it as if it were an alien thing. “Ty,” Jules said, dropping his hand. “Why did you have the bees in your room? What is it you like about them?”

Ty said nothing.

“You like the way they work together, right?” Julian said. “Well, we have to work together now. We’re going to get to the office and make a call out to the Clave, okay? A distress call. So they’ll send backup to protect us.”

Ty held his hand out for the dagger with a curt nod. “That’s what I would have suggested if Mark and Katerina had listened to me.”

“He would have,” Livvy said. She had taken the dagger with more confidence than Ty, and held it as if she knew what she was doing with the blade. “It’s what he was thinking about.”

“We’re going to have to be very quiet now,” Jules said. “You two are going to follow me to the office.” He raised his eyes; his gaze met Emma’s. “Emma’s going to get Tavvy and Dru and meet us there. Okay?”

Emma’s heart swooped and plummeted like a seabird. Octavius—Tavvy, the baby, only two years old. And Dru, eight, too young to start physical training. Of course someone was going to have to get them both. And Jules’s eyes were pleading.

“Yes,” she said. “That’s exactly what I’m going to do.”

Cortana was strapped to Emma’s back, a throwing knife in her hand. She thought she could feel the metal pulsing through her veins like a heartbeat as she slipped down the Institute corridor, her back to the wall. Every once in a while the hallway would open out into windows, and the sight of the blue sea and the green mountains and the peaceful white clouds would tease her. She thought of her parents, somewhere out on the beach, having no idea what was happening at the Institute. She wished they were here, and at the same time was glad they weren’t. At least they were safe.

She was in the part of the Institute that was most familiar to her now: the family quarters. She slipped past Helen’s empty bedroom, clothes packed up and her coverlet dusty. Past Julian’s room, familiar from a million sleepovers, and Mark’s, door firmly shut. The next room was Mr. Blackthorn’s, and just beside it was the nursery. Emma took a deep breath and shouldered the door open.

The sight that met her eyes in the little blue-painted room made them widen. Tavvy was in his crib, his small hands clutching the bars, cheeks bright red from screaming. Drusilla stood in front of the crib, a sword—Angel knew where she’d gotten it—clutched in her hand; it was pointed directly at Emma. Dru’s hand was shaking enough that the point of the sword was dancing around; her braids stuck out on either side of her plump face, but the look in her Blackthorn eyes was one of steely determination: Don’t you dare touch my brother.

“Dru,” Emma said as softly as she could. “Dru, it’s me. Jules sent me to get you.”

Dru dropped the sword with a clatter and burst into tears. Emma swept past her and seized the baby out of his crib with her free arm, heaving him up onto her hip. Tavvy was small for his age but still weighed a good twenty-five pounds; she winced as he clutched onto her hair.

“Memma,” he said.

“Shush.” She kissed the top of his head. He smelled like baby powder and tears. “Dru, grab onto my belt, okay? We’re going to the office. We’ll be safe there.”

Dru took hold of Emma’s weapons belt with her small hands; she’d already stopped crying. Shadowhunters didn’t cry much, even when they were eight.

Emma led the way out into the hall. The sounds from below were worse now. The screams were still going on, the deep howling, the sounds of glass breaking and wood ripping. Emma inched forward, clutching Tavvy, murmuring over and over that everything was all right, he’d be all right. And there were more windows, and the sun slashed through them viciously, almost blinding her.

She was blinded, by panic and the sun; it was the only explanation for the wrong turn she took next. She turned down a corridor, and instead of finding herself in the hallway that she expected, she found herself standing atop the wide staircase that led down to the foyer and the large double doors that were the building’s entrance.