“That’s what I’m afraid of,” Clary whispered.

“What?”

“That I don’t have any more miracles in me,” she said, and pressed her lips together as the others joined them, Jace looking curiously from Simon to Clary as if wondering what they had been talking about.

Isabelle gazed out over the plain, at the acres of bleakness ahead, the view choked with dust. “Did you see something?”

“What about those caves?” Simon asked, gesturing toward the dark entrances tunneling into the mountainside. “They’re shelter—”

“Good idea,” Jace said. “We’re in a demon dimension, God knows what lives here, and you want to crawl into a narrow dark hole and—”

“All right,” Simon interrupted. “It was just a suggestion. You don’t need to get pissed off—”

Jace, who was clearly in a mood, gave him a cold look. “That wasn’t me pissed off, vampire—”

A dark piece of cloud detached itself from the sky and darted suddenly downward, faster than any of them could follow. Clary caught a single horrible glimpse of wings and teeth and dozens of red eyes, and then Jace was rising up into the air, caught in the clawed grip of an airborne demon.

Isabelle screamed. Clary’s hand went to her belt, but the demon had already shot back up into the sky, a whirl of leathery wings, emitting a high-pitched squeal of victory. Jace made no noise at all; Clary could see his boots dangling, motionless. Was he dead?

Her vision went white. Clary whirled on Alec, who already had his bow out, an arrow notched and ready.

“Shoot it!” she screamed.

He spun like a dancer, scanning the sky. “I can’t get a clear shot; it’s too dark—I could hit Jace—”

Isabelle’s whip uncoiled from her hand, a glimmering wire, reaching up, up, impossibly up. Its shimmering light illuminated the clouded sky, and Clary heard the demon scream again, this time a shrill cry of pain. The creature was spinning through the air, tumbling over and over, Jace caught in its grip. Its claws were sunk deep into his back—or was he clinging to it? Clary thought she saw the gleam of a seraph blade, or it might only have been the shimmer of Izzy’s whip as it reached up, and then fell back to earth in a brightening coil.

Alec swore, and let an arrow fly. It shot upward, piercing the darkness; a second later a heaving dark mass plummeted to earth and hit the ground with a whump that sent up a cloud of powdery ash.

They all stared. Splayed, the demon was large, almost the size of a horse, with a dark green, turtle-like body; limp, leathery wings; six centipede-like clawed appendages; and a long stem of a neck that ended in a circle of eyes and jagged, uneven teeth. The shaft of Alec’s arrow protruded from its side.

Jace was kneeling on its back, a seraph blade in his hand. He plunged it down into the back of the creature’s neck viciously, over and over, sending up small geysers of black ichor that sprayed his clothes and face. The demon gave a squealing gurgle and slumped, its multiple red eyes going blank and lightless.

Jace slid from its back, breathing hard. The seraph blade had already begun to warp and twist with ichor; he tossed it to the side and looked levelly at the small group of his friends, all staring at him with expressions of astonishment.

“That,” he said, “was me pissed off.”

Alec made a sound halfway between a groan and an expletive, and lowered his bow. His black hair was stuck to his forehead with sweat.

“You don’t all have to look so worried,” Jace said. “I was doing fine.”

Clary, light-headed with relief, gasped. “Fine? If your definition of ‘fine’ suddenly includes becoming a snack for a flying death turtle, then we are going to have to have words, Jace Lightwood—”

“It didn’t vanish,” Simon interrupted, looking as stunned as the rest of them. “The demon. It didn’t vanish when you killed it.”

“No, it didn’t,” Isabelle said. “Which means its home dimension is here.” Her head was craned back, and she was studying the sky. Clary could see the gleam of a newly applied Farsighted rune on her neck. “And apparently these demons can go out in the daylight. Probably because the sun here is almost burnt out. We need to get out of this area.”

Simon coughed loudly. “What were you all saying about taking shelter in the caves being a bad idea?”

“Actually, that was just Jace,” said Alec. “Seems like a fine idea to me.”

Jace glared at them both, and scrubbed a hand across his face, succeeding in smearing the black ichor across his cheek. “Let’s check the caves out. We’ll find a small one, scout it thoroughly before we rest. I’ll take first watch.”

Alec nodded and started to move toward the nearest cave entrance. The rest of them followed; Clary fell into step beside Jace. He was silent, lost in thought; under the heavy cloud cover, his hair glinted a dull gold, and she could see the massive rips in the back of his gear jacket where the demon’s claws had taken hold. The corner of his mouth quirked up suddenly.

“What?” Clary demanded. “Is something funny?”

“ ‘Flying death turtle’?” he said. “Only you.”

“ ‘Only me’? Is that good or bad?” she asked as they reached the cave entrance, looming up before them like an open, dark mouth.

Even in the shadows his smile was quicksilver. “It’s perfect.”

They made it only a few feet into the tunnel before they found the way blocked with a metal gate. Alec cursed, looking back over his shoulder. The cave entrance was just behind them, and through it Clary could see orange sky and dark, circling shapes.

“No—this is good,” Jace said, stepping closer to the gate. “Look. Runes.”

Runes were indeed worked into the curves of the metal: some familiar, some Clary didn’t know. Still, they spoke to her of protection, of the fending off of demonic forces, a whisper in the back of her head. “They’re protection runes,” she said. “Protection against demons.”

“Good,” said Simon, casting another anxious glance back over his shoulder. “Because the demons are coming—fast.”

Jace shot a glance behind them, then seized the gate and yanked at it. The lock burst, shedding flakes of rust. He pulled again, harder, and the gate swung open; Jace’s hands were shimmering with suppressed light, and the metal where he had touched it looked blackened.

He ducked into the darkness beyond, and the others followed, Isabelle reaching for her witchlight. Simon came after, then Alec last, reaching out to slam the gate shut behind them. Clary took a moment to add a locking rune, just to be sure.

Izzy’s witchlight flared up, illuminating the fact that they were standing in a tunnel that snaked forward into darkness. The walls were smooth, marbled gneiss, carved over and over again with runes of protection, holiness, and defense. The floor was sanded stone, easy to walk on. The air grew clearer as they made their way deeper into the mountain, the taint of fog and demons slowly receding until Clary was breathing more easily than she had since they had come to this realm.

They emerged at last into a large circular space, clearly crafted by human hands. It looked like the inside of a cathedral dome: round, with a massive ceiling arching overhead. There was a fire pit in the center of the room, long gone cold. White stone gems had been set into the ceiling. They glowed softly, filling the room with dim illumination. Isabelle lowered her witchlight, letting it blink off in her hand.