It shot toward Matthew, who swore and slashed out at it with his seraph blade. Cordelia charged forward, only to be met with another of the Khora demons. The demon had shed several others: two leaped toward Christopher and Thomas, springing through the air like black spiders. Lucie ran to join them, impaling one of the Khora from behind: it vanished, spattering ash and ichor, as Christopher and Thomas dispatched the other.

Cordelia whipped Cortana forward with a slashing motion, shredding the demon in front of her with such force that the blade passed through the Khora, carried on, and embedded itself in the granite railing of the bridge. She yanked it free as the demon disappeared with a howl. The blade of Cortana was smeared with black, but it was undamaged. I suppose it really can cut anything, she thought dazedly, before turning to rejoin the battle.

She pushed forward as James hurled a knife, pinning one of the shadow demons to the cables of the bridge like a hideous butterfly. It struggled and hissed as Matthew and James leaped up onto the bridge’s railing, their seraph blades blazing in their hands as they slew shadow after shadow.

But it didn’t matter how many of these shadow creatures they killed, Cordelia knew. The Mandikhor could make an infinite number of Khora: it was the source of them, and the source had to be destroyed.

“Christopher!” she heard Thomas shout. She spun and saw that a group of Khora were starting to circle Christopher. Even as Christopher tried to fight his way free, the circle tightened. Lucie and Thomas raced toward him—James and Matthew leaped down from the railing—but Cordelia, raising her sword, raced the other way, toward the Mandikhor.

It had been watching Christopher and the others, licking its lips as the Khora closed in. Now it reared back as Cordelia approached, but too late—she hurled herself forward, Cortana sinking deep into the creature’s torso. Hot ichor spilled onto her hand, and the world seemed to tilt around her, the color rushing out of it like blood from a wound. She stood on the bridge among black-and-white shadows and twisted, gnarled trees—the suspension cables hung like rotting vines, blackening in the night air. She yanked Cortana back, gasping, and fell to her knees. Suddenly she felt a hand on her arm. She was wrenched to her feet and looked with surprise at Matthew, staring at her, his face very white. “Cordelia—”

“She’s all right!” It was Lucie, spattered with blood and ichor, clutching the Pyxis box. The others had fanned out around Cordelia: James had his blade in one hand, his gaze trained on the roaring, bleeding Mandikhor.

The bridge was empty of Khora. Cordelia had distracted the Mandikhor just long enough for the others to kill the shadow creatures; but the Mandikhor was growling now, another lump already beginning to swell on its back. “Now!” Lucie cried. “We must get it into the Pyxis!”

“Put the box on the ground!” It was Thomas, vaulting up onto the railing, his bolas in his hand. “Christopher, say the words!”

Christopher stepped closer to the Pyxis. The Mandikhor, realizing what was happening at last, charged.

Christopher shouted, in a voice that cut through the noise of battle: “Thaam Tholach Thechembaor!”

The alchemical symbols carved on the Pyxis box lit as if the lines on the wood were burning: they seemed to bloom on the wood, glowing like coals.

A spear of light shot from the Pyxis, and then another, and another. The beams of light arrowed along the bridge, wrapping around the Mandikhor in a bright cage. It gave a howl—the cage of light flared up one last time and was sucked back into the Pyxis, the Mandikhor vanishing with it.

There was a long silence. James mopped at the blood on his face, his golden eyes burning. Matthew’s hand was still wrapped around Cordelia’s arm.

“I don’t mean to put a damper on things,” said Thomas at last, “but—did that work? Because it seems rather—”

The Pyxis exploded. The Shadowhunters yelled and dived out of the way as wooden shrapnel blew in all directions. Wind tore across the bridge, flattening Cordelia to her knees, a howling hurricane of fire-scented air.

At last the howling died down. The bridge was empty and silent, only the wind blowing a bit of discarded refuse back and forth across the roadway. Cordelia rose to her feet and reached down a hand to help Lucie up after her. Ahead, she could still see the glimmering light of Magnus’s bridge, mundane traffic still making its way across it.

“—too easy,” Thomas finished. His face was smeared with soot.

“Bloody hell,” said James, reaching for a knife, just as the world seemed to explode around them.

* * *

Out of the wind and air, the Mandikhor suddenly appeared, twice as big as it had been before, and clothed in ragged darkness. It rose above them like a shadow drawn in blood, its head thrown back, each of its talons gleaming like a dagger.

James flung his knife just as the Mandikhor sprang toward him, shadows spilling from it and racing across the bridge in all directions. The world had turned gray and black again. James could see London on either side of the river, but it was a ruined London, the Tower shattered and broken, fires burning along the wharves, the blackened spires of churches standing as skeletons against a smoke-stained sky. He could hear his friends all around him, their shouts and cries as they fought back the shadows, but he could no longer see them. He was alone in his nightmare realm.

The Mandikhor leaped toward him and seized hold of him. James had been braced for an attack, but this was something different: the demon was holding him fast, claws sunk into the front of his gear jacket. Its lips curled back from its teeth. “Come with me,” the demon hissed. “Come with me, child of demons, to where you will be honored. You see the same world I do. You see the world as it really is. I know who your mother is, and who your grandfather is. Come with me.”

James went cold.

I know who your mother is, and who your grandfather is. He thought of the demon in the park: Why destroy your own kind?

“I am a Shadowhunter,” he said. “I will not listen to your lies.”

“You know I speak the truth,” said the Mandikhor, its hot breath searing James’s skin. “I swear on the names of Asmodeus, of Belial, of Belphegor and Sammael, that I can end this scourge if you will come with me. No more need die.”

James froze. A demon, swearing on the names of the Princes of Hell. A voice in the back of his head screamed, Do it! Go with him! End the sickening, the dying! Another voice, quieter but steadier, whispered, Demons lie. Even when they swear, they lie.

“No,” he said, but his voice shook.

The Mandikhor hissed. “So ungrateful,” it said. “You alone can walk between the world of Earth and the dark kingdom.”

James stared into the demon’s blood-red eyes. “Do you mean the kingdom of Belphegor?”

The Mandikhor made an awful noise; after a moment, James realized it was chuckling. “So like a human,” it said, “to know so much, and yet know so little.”

James opened his mouth to speak, just as an arcing golden light seared the air. “Leave him alone!” Cordelia shouted, as Cortana divided the darkness.

James jerked free, rolling away from the demon and up onto his feet as Cordelia threw herself at the Mandikhor. The gold of the sword was the only color in the black-and-white world—the gold and the flame-red of her hair. Cortana whipped back and forth—its blade slashed across the demon’s chest, opening a long black wound—the demon howled and struck out, its massive paw slamming into Cordelia and sending her flying. Cortana tumbled from her hand, skidding across the bridge as she hurtled over the railing with a scream.

James heard Lucie scream, “Daisy!” and the sound of a distant splash. The world seemed to go silent as he bent to seize up Cortana. He strode toward the Mandikhor, his blood burning.

The demon had sunk to its forelegs. It was bleeding from the wound Cordelia had dealt it, ichor spreading around it like a shadow. “You cannot slay me here,” it snarled as James came near. “My roots are deep within another realm. As I feed there, I grow stronger. I am a legion who cannot be touched.” With a final hiss, it vanished.

Color sprang back into the world. James spun, Cortana in hand: he could see the bridge as it had always been, dull gold and white in the moonlight, and his friends running toward him. He did not see Lucie. He remembered her calling out Cordelia’s name. He remembered the sound of the water. Cordelia. Cordelia.

“Where is she?” Matthew gasped as he neared James. “Where’s Cordelia?”

“She’s in the river,” James said, and began to run.

* * *

Lucie stared frantically at the river. She could see steps leading down to it from what looked like a passage through a building beside the bridge. She hurtled down the stairs to ground level and found herself in a dimly lit, narrow street lined with tall warehouses, blackened with soot and grime. There was the passage, a dark hole in the nearest building. She ran to it and saw stone stairs descending to a faint gleam at the bottom: the river. She raced to where an old cobbled ramp led into the water, an empty barge moored beside it. The river flowed by, black and silent, under the clouded sky; mist rose from the water.

There was no sign of Cordelia. Panic mounted in Lucie’s stomach as she stared out into the black water. She didn’t know if Cordelia could swim, and even a strong swimmer could drown in the currents of the Thames. And what if Cordelia had hit her head, or had been knocked out by the long fall from the bridge?

A sob caught in her throat. She dropped her seraph blade, which sputtered against the muddy pebbles of the bank, and began to fumble with the buttons of her gear jacket. The water didn’t look very deep. She wasn’t a strong swimmer, but she could try.

In the distance, she could see the fog-enshrouded shape of a barge arrowing slowly down the center of the river. “Help!” she shouted. “Help! Someone has fallen in the river!” She raced along the bank, waving frantically at the barge, which was disappearing into the mist. “Bring her out, please!” Lucie screamed. “Help me!”

But the barge had vanished. She could see figures on the bridge above her, the eerie light of seraph blades. The boys were still fighting. She could never reach Magnus in time, nor could he put aside what he was doing: he had to remain utterly focused on the illusion of the false bridge. She would have to go into the river, even if she might drown herself.