But there were no signs of destruction. Bathed in pleasant afternoon light, the brownstone seemed to glow. Bees droned lazily around the rosebushes under Madame Dorothea’s windows.

“It looks the same,” Clary said.

“On the outside.” Jace reached into his jeans pocket and drew out another one of the metal and plastic contraptions she’d mistaken for a cell phone.

“So that’s a Sensor? What does it do?” she asked.

“It picks up frequencies, like a radio does, but these frequencies are demonic in origin.”

“Demon shortwave?”

“Something like that.” Jace held the Sensor out in front of him as he approached the house. It clicked faintly as they climbed the stairs, then stopped. Jace frowned. “It’s picking up trace activity, but that could just be left over from that night. I’m not getting anything strong enough for there to be demons present now.”

Clary let out a breath she hadn’t realized she’d been holding. “Good.” She bent to retrieve her keys. When she straightened up, she saw the scratches on the front door. It must have been too dark for her to have seen them last time. They looked like claw marks, long and parallel, raked deeply into the wood.

Jace touched her arm. “I’ll go in first,” he said. Clary wanted to tell him that she didn’t need to hide behind him, but the words wouldn’t come. She could taste the terror she’d felt when she’d first seen the Ravener. The taste was sharp and coppery on her tongue like old pennies.

He pushed the door open with one hand, beckoning her after him with the hand that held the Sensor. Once inside the entryway, Clary blinked, adjusting her eyes to the dimness. The bulb overhead was still out, the skylight too filthy to let in any light, and shadows lay thick across the chipped floor. Madame Dorothea’s door was firmly shut. No light showed through the gap under it. Clary wondered uneasily if anything had happened to her.

Jace raised his hand and ran it along the banister. It came away wet, streaked with something that looked blackish red in the dim light. “Blood.”

“Maybe it’s mine.” Her voice sounded tinny. “From the other night.”

“It’d be dry by now if it were,” Jace said. “Come on.”

He headed up the stairs, Clary close behind him. The landing was dark, and she fumbled her keys three times before she managed to slide the right one into the lock. Jace leaned over her, watching impatiently. “Don’t breathe down my neck,” she hissed; her hand was shaking. Finally the tumblers caught, the lock clicking open.

Jace pulled her back. “I’ll go in first.”

She hesitated, then stepped aside to let him pass. Her palms were sticky, and not from the heat. In fact, it was cool inside the apartment, almost cold—chilly air seeped from the entryway, stinging her skin. She felt goose bumps rising as she followed Jace down the short hallway and into the living room.

It was empty. Startlingly, entirely empty, the way it had been when they’d first moved in—the walls and floor bare, the furniture gone, even the curtains torn down from the windows. Only faint lighter squares of paint on the wall showed where her mother’s paintings had hung. As if in a dream, Clary turned and walked toward the kitchen, Jace pacing her, his light eyes narrowed.

The kitchen was just as empty, even the refrigerator gone, the chairs, the table. The kitchen cabinets stood open, their bare shelves reminding her of a nursery rhyme. She cleared her throat. “What would demons,” she said, “want with our microwave?”

Jace shook his head, mouth curling under at the corners. “I don’t know, but I’m not sensing any demonic presence right now. I’d say they’re long gone.”

She glanced around one more time. Someone had cleaned up the spilled Tabasco sauce, she noticed distantly.

“Are you satisfied?” Jace asked. “There’s nothing here.”

She shook her head. “I want to see my room.”

He looked as if he were about to say something, then thought better of it. “If that’s what it takes,” he said, sliding the seraph blade into his pocket.

The light in the hallway was out, but Clary didn’t need much light to navigate inside her own house. With Jace just behind her, she found the door to her bedroom and reached for the knob. It was cold in her hand—so cold it nearly hurt, like touching an icicle with your bare skin. She saw Jace look at her quickly, but she was already turning the knob, or trying to. It moved slowly, almost stickily, as if the other side of it were embedded in something glutinous and syrupy—

The door blew outward, knocking her off her feet. She skidded across the hallway floor and slammed into the wall, rolling onto her stomach. There was a dull roaring in her ears as she pulled herself up to her knees.

Jace, flat against the wall, was fumbling in his pocket, his face a mask of surprise. Looming over him like a giant in a fairy tale was an enormous man, big around as an oak tree, a broad-bladed ax clutched in one gigantic dead-white hand. Tattered filthy rags hung off his grimy skin, and his hair was a single matted tangle, thick with dirt. He stank of poisonous sweat and rotting flesh. Clary was glad she couldn’t see his face—the back of him was bad enough.

Jace had the seraph blade in his hand. He raised it, calling out: “Sansanvi!”

A blade shot from the tube. Clary thought of old movies where bayonets were hidden inside walking sticks, released at the flick of a switch. But she’d never seen a blade like this before: clear as glass, with a glowing hilt, wickedly sharp and nearly as long as Jace’s forearm. He struck out, slashing at the gigantic man, who staggered back with a bellow.

Jace whirled around, racing toward her. He caught her arm, hauling her to her feet, pushing her ahead of him down the hall. She could hear the thing behind them, following; its footsteps sounded like lead weights being dropped onto the floor, but it was coming on fast.

They sped through the entryway and out onto the landing, Jace whipping around to slam the front door shut. She heard the click of the automatic lock and caught her breath. The door shook on its hinges as a tremendous blow struck against it from inside the apartment. Clary backed away to the stairs. Jace glanced at her. His eyes were glowing with manic excitement. “Get downstairs! Get out of the—”

Another blow came, and this time the hinges gave way and the door flew outward. It would have knocked Jace over if he hadn’t moved so fast that Clary barely saw it; suddenly he was on the top stair, the blade burning in his hand like a fallen star. She saw Jace look at her and shout something, but she couldn’t hear him over the roar of the gigantic creature that burst from the shattered door, making straight for him. She flattened herself against the wall as it passed in a wave of heat and stink—and then its ax was flying, whipping through the air, slicing toward Jace’s head. He ducked, and it thunked heavily into the banister, biting deep.

Jace laughed. The laugh seemed to enrage the creature; abandoning the ax, he lurched at Jace with his enormous fists raised. Jace brought the seraph blade around in an arcing sweep, burying it to the hilt in the giant’s shoulder. For a moment the giant stood swaying. Then he lurched forward, his hands outstretched and grasping. Jace stepped aside hastily, but not hastily enough: The enormous fists caught hold of him as the giant staggered and fell, dragging Jace in his wake. Jace cried out once; there was a series of heavy and cracking thumps, and then silence.

Clary scrambled to her feet and raced downstairs. Jace lay sprawled at the foot of the steps, his arm bent beneath him at an unnatural angle. Across his legs lay the giant, the hilt of Jace’s blade protruding from his shoulder. He was not quite dead, but flopping weakly, a bloody froth leaking from his mouth. Clary could see his face now—it was dead-white and papery, latticed with a black network of horrible scars that almost obliterated his features. His eye sockets were red suppurating pits. Fighting the urge to gag, Clary stumbled down the last few stairs, stepped over the twitching giant, and knelt down next to Jace.

He was so still. She laid a hand on his shoulder, felt his shirt sticky with blood—his own or the giant’s, she couldn’t tell. “Jace?”

His eyes opened. “Is it dead?”

“Almost,” Clary said grimly.

“Hell.” He winced. “My legs—”

“Hold still.” Crawling around to his head, Clary slipped her hands under his arms and pulled. He grunted with pain as his legs slipped out from under the creature’s spasming carcass. Clary let go, and he struggled to his feet, his left arm across his chest. She stood up. “Is your arm all right?”

“No. Broken,” he said. “Can you reach into my pocket?”

She hesitated, nodded. “Which one?”

“Inside jacket, right side. Take out one of the seraph blades and hand it to me.” He held still as she nervously slipped her fingers into his pocket. She was standing so close that she could smell the scent of him, sweat and soap and blood. His breath tickled the back of her neck. Her fingers closed on a tube and she drew it out, not looking at him.

“Thanks,” he said. His fingers traced it briefly before he named it: “Sanvi.” Like its predecessor, the tube grew into a wicked-looking dagger, its glow illuminating his face. “Don’t watch,” he said, going to stand over the scarred thing’s body. He raised the blade over his head and brought it down. Blood fountained from the giant’s throat, splattering Jace’s boots.

She half-expected the giant to vanish, folding in on itself the way the kid in Pandemonium had. But it didn’t. The air was full of the smell of blood: heavy and metallic. Jace made a sound low in his throat. He was white-faced, whether with pain or disgust she couldn’t tell. “I told you not to watch,” he said.

“I thought it would disappear,” she said. “Back to its own dimension—you said.”

“I said that’s what happens to demons when they die.” Wincing, he shrugged his jacket off his shoulder, baring the upper part of his left arm. “That wasn’t a demon.” With his right hand he drew something out of his belt. It was the smooth wand-shaped object he’d used to carve those overlapping circles into Clary’s skin. Looking at it, she felt her forearm begin to burn.

Jace saw her staring and grinned the ghost of a grin. “This,” he said, “is a stele.” He touched it to an inked mark just below his shoulder, a curious shape almost like a star. Two arms of the star jutted out from the rest of the mark, unconnected. “And this,” he said, “is what happens when Shadowhunters are wounded.”

With the tip of the stele, he traced a line connecting the two arms of the star. When he lowered his hand, the mark was shining as if it had been etched with phosphorescent ink. As Clary watched, it sank into his skin, like a weighted object sinking into water. It left behind a ghostly reminder: a pale, thin scar, almost invisible.

An image rose in Clary’s mind. Her mother’s back, not quite covered by her bathing suit top, the blades of her shoulders and curves of her spine dappled with narrow, white marks. It was like something she had seen in a dream—her mother’s back didn’t really look like that, she knew. But the image nagged at her.

Jace let out a sigh, the tense look of pain leaving his face. He moved the arm, slowly at first, then more easily, lifting it up and down, clenching his fist. Clearly it was no longer broken.

“That’s amazing,” Clary said. “How did you—?”

“That was an iratze—a healing rune,” Jace said. “Finishing the rune with the stele activates it.” He shoved the slim wand into his belt and shrugged his jacket back on. With the toe of his boot he prodded the giant’s corpse. “We’re going to have to report this to Hodge,” he said. “He’ll freak out,” he added, as if the thought of Hodge’s alarm gave him some satisfaction. Jace, Clary thought, was the sort of person who liked it when things were happening, even things that were bad.

“Why will he freak?” Clary said. “And I get that that thing isn’t a demon—that’s why the Sensor didn’t register it, right?”

Jace nodded. “You see the scars all over its face?”

“Yes.”

“Those were made with a stele. Like this one.” He tapped the wand in his belt. “You asked me what happens when you carve Marks onto someone who doesn’t have Shadowhunter blood. Just one Mark will only burn you, but a lot of Marks, powerful ones? Carved into the flesh of a totally ordinary human being with no trace of Shadowhunter ancestry? You get this.” He jerked his chin at the corpse. “The runes are agonizingly painful. The Marked ones go insane—the pain drives them out of their minds. They become fierce, mindless killers. They don’t sleep or eat unless you make them, and they die, usually quickly. Runes have great power and can be used to do great good—but they can be used for evil. The Forsaken are evil.”

Clary stared at him in horror. “But why would anyone do that to themselves?”

“Nobody would. It’s something that gets done to them. By a warlock, maybe, some Downworlder gone bad. The Forsaken are loyal to the one who Marked them, and they’re fierce killers. They can obey simple commands, too. It’s like having a—a slave army.” He stepped over the dead Forsaken, and glanced over his shoulder at her. “I’m going back upstairs.”

“But there’s nothing there.”

“There might be more of them,” he said, almost as if he were hoping there would be. “You should wait here.” He started up the steps.

“I wouldn’t do that if I were you,” said a shrill and familiar voice. “There are more of them where the first one came from.”