“They were low,” Jace growled.

“Your version of low must be different from mine!” Alec shouted, as the thing that had once been Dorothea howled and twisted. It seemed to be spreading, humped and knobbled and grotesquely misshapen—

Clary tore her eyes away as Jace stood, pulling her after him. Isabelle and Alec stumbled to their feet, gripping their weapons. The hand holding Isabelle’s whip was trembling slightly.

“Move!” Jace shoved Clary toward the apartment door. When she tried to look back over her shoulder, she saw only a thickly swirling grayness, like storm clouds, a dark shape at its center …

The four of them burst out into the foyer, Isabelle in the lead. She raced toward the front door, tried it, and turned with a stricken face. “It’s resistant. Must be a spell—”

Jace swore and fumbled in his jacket. “Where the hell is my stele?”

“I have it,” Clary said, remembering. As she reached for her pocket, a noise like thunder exploded through the room. The floor heaved under her feet. She stumbled and nearly fell, catching at the banister for support. When she looked up, she saw a gaping new hole in the wall separating the foyer from Dorothea’s apartment, lined all around its ragged edges with wood and plaster rubble, through which something was climbing—almost oozing—

“Alec!” It was Jace, shouting: Alec was standing in front of the hole, white-faced and horrified-looking. Swearing, Jace ran up and grabbed him, dragging him back just as the oozing thing pulled itself free of the wall and into the foyer.

Clary heard her breath catch. The creature’s flesh was livid and bruised-looking. Through the seeping skin, bones protruded—not new white bones, but bones that looked as if they had been in the earth a thousand years, black and cracked and filthy. Its fingers were stripped and skeletal, its thin-fleshed arms pocked with dripping black sores through which more yellowing bone was visible. Its face was a skull, its nose and eyes caved-in holes. Its taloned fingers brushed the floor. Tangled around its wrists and shoulders were bright swatches of cloth: all that remained of Madame Dorothea’s silk scarves and turban. It was at least nine feet tall.

It looked down at the four teenagers with empty eye sockets. “Give me,” it said, in a voice like the wind blowing trash across empty pavement, “the Mortal Cup. Give it to me, and I will let you live.”

Panicked, Clary stared at the others. Isabelle looked as if the sight of the thing had hit her like a punch to the stomach. Alec was motionless. It was Jace, as always, who spoke. “What are you?” he asked, voice steady, though he looked more rattled than Clary had ever seen him.

The thing inclined its head. “I am Abbadon. I am the Demon of the Abyss. Mine are the empty places between the worlds. Mine is the wind and the howling darkness. I am as unlike those mewling things you call demons as an eagle is unlike a fly. You cannot hope to defeat me. Give me the Cup or die.”

Isabelle’s whip trembled. “It’s a Greater Demon,” she said. “Jace, if we—”

“What about Dorothea?” Clary’s voice came shrilly out of her mouth before she could stop it. “What happened to her?”

The demon’s empty eyes swung to regard her. “She was a vessel only,” it said. “She opened the Portal and I took possession of her. Her death was swift.” Its gaze moved to the Cup in her hand. “Yours will not be.”

It began to move toward her. Jace blocked its way, the glittering sword in one hand, a seraph blade appearing in the other. Alec was watching him, his expression sick with horror.

“By the Angel,” Jace said, looking the demon up and down. “I knew Greater Demons were meant to be ugly, but no one ever warned me about the smell.”

Abbadon opened its mouth and hissed. Inside its mouth were two rows of jagged glass-sharp teeth.

“I’m not so sure about this wind and howling darkness business,” Jace went on, “smells more like landfill to me. You sure you’re not from Staten Island?”

The demon leaped at him. Jace whipped his blades up and outward with an almost frightening speed; both sank into the fleshiest part of the demon, its abdomen. It howled and struck at him, knocking him aside the way a cat might bat aside a kitten. Jace rolled and got to his feet, but Clary could see from the way he was holding his arm that he’d been hurt.

That was enough for Isabelle. Darting forward, she lashed out at the demon with her whip. It struck the demon’s gray hide, and a red weal appeared, welling blood. Abbadon ignored her, moving toward Jace.

With his uninjured hand Jace drew out a second seraph blade. He whispered to it and it sprang free, bright and gleaming. He raised it as the demon loomed up before him; he looked impossibly small in front of it, a child dwarfed by a monster. And he was grinning, even as the demon reached for him. Isabelle, screaming, lashed at it, sending blood in a thick spray across the floor—

The demon struck, its razored hand lashing down at Jace. Jace staggered back, but he was unharmed. Something had thrown itself between him and the demon, a slim black shadow with a gleaming blade in its hand. Alec. The demon shrieked—Alec’s featherstaff had pierced its skin. With a snarl it struck again, bone-talons catching Alec a vicious blow that lifted him off his feet and hurled him against the far wall. He struck with a sickening crunch and slid to the floor.

Isabelle screamed her brother’s name. He didn’t move. Lowering the whip, she started to run to him. The demon, turning, caught her a backhanded blow that sent her spinning to the ground. Coughing blood, Isabelle started to get to her feet; Abbadon knocked her down again, and this time she lay still.

The demon moved toward Clary.

Jace stood frozen, staring at Alec’s crumpled body like someone caught in a dream. Clary screamed as Abbadon neared her. She began to back up the stairs, stumbling on the broken steps. The stele burned against her skin. If only she had a weapon, anything—

Isabelle had clawed her way into a sitting position. Pushing her bloody hair back, she screamed at Jace. Clary heard her own name in Isabelle’s screams and saw Jace, blinking as if slapped awake, spin toward her. He began to run. The demon was close enough now that Clary could see the black sores on its skin, could see that there were things crawling inside them. It reached for her—

But Jace was there, knocking Abbadon’s hand aside. He flung the seraph blade at the demon; it stuck in the creature’s chest, next to the two blades already there. The demon snarled as if the blades were no more than an annoyance.

“Shadowhunter,” it snarled. “I shall take pleasure in killing you, in hearing your bones crunch as your friend’s did—”

Springing onto the banister, Jace flung himself at Abbadon. The force of the jump knocked the demon backward; it staggered, Jace clinging to its back. He seized a seraph blade out of its chest, sending up a spray of ichor, and brought the blade down, again and again, into the demon’s back, its shoulders running with black fluid.

Snarling, Abbadon backed toward the wall. Jace had to drop or be crushed. He fell to the ground, landed lightly, and raised the blade again. But Abbadon was too swift for him; its hand lashed out, knocking Jace into the stairs. Jace went down, a circle of talons at his throat.

“Tell them to give me the Cup,” Abbadon snarled, talons hovering just above Jace’s skin. “Tell them to give it to me and I will let them live.”

Jace swallowed. “Clary—”

But Clary would never know what he would have said, because at that moment the front door flew open. For a moment all she saw was brightness. Then, blinking away the fiery afterimage, she saw Simon standing in the open doorway. Simon. She had forgotten he was outside, had almost forgotten he existed.

He saw her, crouched on the stairs, and his gaze moved past her and over Abbadon and Jace. He reached back over his shoulder. He was holding Alec’s bow, she realized, and the quiver was strapped across his back. He drew an arrow from it, fitted it to the string, and lifted the bow expertly, as if he’d done the same thing a hundred times before.

The arrow sprang free. It made a hot buzzing sound, like a huge bumblebee, as it shot over Abbadon’s head, plunged toward the roof—

And shattered the skylight. Dirty black glass fell like rain, and through the broken pane streamed sunlight, quantities of sunlight, great golden bars of it stabbing downward and flooding the foyer with light.

Abbadon screamed and staggered back, shielding its misshapen head with its hands. Jace put a hand to his unharmed throat, staring in disbelief as the demon crumpled, howling, to the floor. Clary half-expected it to burst into flames, but instead it began to fold in on itself. Its legs collapsed toward its torso, its skull crumpling like burning paper, and within the span of a minute it had vanished entirely, leaving only scorch marks behind.

* * *

Simon lowered the bow. He was blinking behind his glasses, his mouth slightly open. He looked as astonished as Clary felt.

Jace lay on the stairs where the demon had thrown him. He was struggling to sit up as Clary slid down the steps and fell to her knees beside him. “Jace—”

“I’m all right.” He sat up, wiping blood from his mouth. He coughed and spit red. “Alec—”

“Your stele,” she interrupted, reaching for her pocket. “Do you need it to fix yourself?”

He looked at her. The sunlight pouring through the shattered skylight lit his face. He looked as if he were holding himself back from something with a terrible effort. “I’m all right,” he said again, and pushed her aside, none too gently. He got to his feet, staggered, and nearly fell—the first ungraceful thing she’d ever seen him do. “Alec?”

Clary watched him as he limped across the foyer toward his unconscious friend. Then she zipped the Mortal Cup into the pocket of her hoodie and got to her feet. Isabelle had crawled to her brother’s side and was cradling his head in her lap, stroking his hair. His chest rose and fell—slowly, but he was breathing. Simon, leaning against the wall watching them, looked utterly drained. Clary squeezed his hand as she passed him. “Thank you,” she whispered. “That was amazing.”

“Don’t thank me,” he said, “thank the archery program at B’nai B’rith summer camp.”

“Simon, I don’t—”

“Clary!” It was Jace, calling her. “Bring my stele.”

Simon let her go reluctantly. She knelt down next to the Shadowhunters, the Mortal Cup thumping heavily against her side. Alec’s face was white, freckled with drops of blood, his eyes unnaturally blue. His grip on Jace’s wrist left bloody smears. “Did I …” he started, then seemed to see Clary, as if for the first time. There was something in his look she hadn’t expected. Triumph. “Did I kill it?”

Jace’s face twisted painfully. “You—”

“Yes,” Clary said. “It’s dead.”

Alec looked at her and laughed. Blood bubbled up in his mouth. Jace pulled his wrist free, touched his fingers to either side of Alec’s face. “Don’t,” he said. “Hold still, just hold still.”

Alec closed his eyes. “Do what you have to,” he whispered.

Isabelle held her stele out to Jace. “Take it.”

He nodded, and drew the tip of the stele down the front of Alec’s shirt. The material parted as if he’d sliced it with a knife. Isabelle watched him through frantic eyes as he yanked the shirt open, leaving Alec’s chest bare. His skin was very white, marked here and there with old translucent scars. There were other injuries there too: a darkening lattice of claw marks, each hole red and oozing. Jaw set, Jace set the stele to Alec’s skin, moving it back and forth with the ease of long practice. But there was something wrong. Even as he drew the healing marks, they seemed to vanish as if he were writing on water.

Jace threw the stele aside. “Damn it.”

Isabelle’s voice was shrill. “What’s going on?”

“It cut him with its talons,” Jace said. “There’s demon poison in him. The Marks can’t work.” He touched Alec’s face again, gently. “Alec,” he said. “Can you hear me?”

Alec didn’t move. The shadows under his eyes looked blue and as dark as bruises. If it weren’t for his breathing, Clary would have thought he was already dead.

Isabelle bent her head, her hair covering Alec’s face. Her arms were around him. “Maybe,” she whispered, “we could—”

“Take him to the hospital.” It was Simon, standing over them, the bow dangling in his hand. “I’ll help you carry him to the van. There’s Methodist down on Seventh Avenue—”

“No hospitals,” said Isabelle. “We need to get him to the Institute.”

“But—”

“They won’t know how to treat him in a hospital,” said Jace. “He’s been cut by a Greater Demon. No mundane doctor would know how to heal those wounds.”

Simon nodded. “All right. Let’s get him to the car.”

In a stroke of good luck, the van hadn’t been towed. Isabelle draped a dirty blanket across the backseat and they laid Alec down across it, his head on Isabelle’s lap. Jace crouched down on the floor beside his friend. His shirt was stained dark across the sleeves and chest with blood, demon and human. When he looked at Simon, Clary saw that all the gold seemed washed out of his eyes by something she had never seen in them before. Panic.

“Drive fast, mundane,” he said. “Drive like hell was following you.”

Simon drove.

They careened down Flatbush and rocketed onto the bridge, keeping pace with the Q train as it roared over the blue water. The sun was painfully bright in Clary’s eyes, striking hot sparks off the river. She clutched at her seat as Simon took the curving ramp off the bridge at fifty miles an hour.