One of the Riders let out a roar of rage when he saw Kieran. “Traitor!” he snarled.

Kieran dropped a courtly little bow. “Eochaid,” he said, by way of greeting. “And Etarlam.” He winked at the sixth Rider, who made a sour face. “Well met.”

Eochaid lunged for him. Kieran dropped into a half crouch, swinging his sword with a lightness and skill that surprised Emma.

The clash of their blades seemed to signal the beginning of a much larger battle. Julian and Mark had forced the Riders from the steps in the first surprise of their appearance. Now the others poured after them, hounding and worrying at them with blades. Mark, carrying a double-edged straight sword, went for Delan; the twins harried Airmed while Cristina, looking beyond furious, engaged Etarlam.

Julian began to move through the blur of battle, slashing to either side of him, cutting his way toward Emma. His eyes suddenly widened. Behind you!

She spun. It was Ethna, her face twisted into a mask of hatred. Her blades made a scissoring motion—Emma raised Cortana just in time, and Ethna’s double blades closed on it with savage force.

And shattered.

The faerie woman gasped in surprise. A second later she was scrambling back, her hands moving in the air. Julian changed course and leaped after her, but another weapon was taking shape in her grasp, this one with a curved blade like a Persian shamshir.

Julian’s sword slammed against Ethna’s. Emma felt the collision between their weapons. It forked through her like lightning. Suddenly everything was happening very fast: Julian twisted gracefully away from the blade, but the edge of it caught him across the top of the arm. Emma felt the pain of it, her parabatai’s pain, just as she had felt his blade strike Ethna’s. She launched herself at the two of them, but Eochaid rose up in front of her and the point of a sword hurtled toward her face, a silver blur cutting the air.

It fell away to the side. Eochaid howled, a brutal, angry sound, and whirled from her to strike savagely at the figure who had come up behind him, whose blade had pierced his shoulder. Blood stained Eochaid’s bronze armor.

It was Kieran. His hair was a mass of black and white strands, sticky with blood over his temple. His clothes were stained with red, his lip split. He stared at Emma, breathing hard.

Eochaid leaped for him and they began to fight savagely. The world seemed a din of clashing blades: Emma heard a cry and saw Cristina fighting to get to Kit, who had been knocked to the ground by Delan. The Riders had swarmed up to the steps to block the Institute doors. Julian was holding off Ethna; the twins were fighting back-to-back, trying to hack their way up the steps alongside Mark.

Emma began to shove blindly toward Kit, a coldness at her heart. The Riders were too fierce, too strong. They wouldn’t tire.

Delan was standing over Kit, his blade high in the air. Kit was scrambling back on his elbows. A sword flashed in front of Emma; she knocked it away with Cortana, heard someone swear. Delan was staring at Kit intently, as if his face held a mystery. “Who are you, boy?” the Rider demanded, his blade stilled.

Kit wiped blood from his face. There was a dagger near him on the flagstones, just out of reach of his hand. “Christopher Herondale,” he said, his eyes flashing arrogantly. He was a Shadowhunter, Emma thought, through and through; he would never beg for his life.

Delan snorted. “Qui omnia nomini debes,” he said, and began to swing his sword down, just as Emma ducked and rolled under the blade, Cortana flashing up, shearing through Delan’s wrist.

The faerie warrior screamed, an echoing howl of rage and pain. The air was full of a mist of blood. Delan’s hand thumped to the ground, still gripping his sword; a second later Kit was on his feet, snatching up the weapon, his eyes blazing. Emma was beside him; together they began to back Delan up, his blood painting the flagstones beneath them as he retreated.

But Delan was laughing. “Slay me if you think you can,” he sneered. “But look around you. You have already lost.”

Kit had his blade up, pointed directly at Delan’s throat. “You look,” he said steadily. “I’ll stab.”

Emma’s head snapped around. Airmed had backed Ty and Livvy against a wall. Ethna had her weapon at Julian’s throat. Cristina had been driven to her knees by Etarlam. Mark was looking at her in horror but couldn’t move—Eochaid had his sword against Mark’s back, just where he could sever his spine.

Karn stood at the top of the steps, his blade out, grinning across his cruel and lovely face.

Emma swallowed. Kit swore softly under his breath. Karn spoke, his teeth flashing white with his smile. “Give us the Black Volume,” he said. “We will let you go.”

Kieran stood frozen, staring from Mark to Cristina. “Do not listen!” he cried. “The Riders are wild magic—they can lie.”

“We don’t have the book,” Julian said steadily. “We’ve never had it. Nothing has changed.”

He looked calm, but Emma could see beneath the surface of him, behind his eyes. She could hear the noise of his thundering heart. He was looking at her, at Mark, at Ty and Livvy, and he was mortally terrified.

“You are asking for something we cannot do,” said Julian. “But maybe we can make a deal. We can swear to you that we will bring you the book when we find it—”

“Your oaths mean nothing,” snarled Ethna. “Let us kill them now and send a message to the Queen, that her tricks will not be countenanced!”

Karn laughed. “Wise words, sister,” he said. “Ready your blades—”

Emma’s hand clamped down on Cortana. Her mind whirled—she couldn’t kill them all, couldn’t prevent what they were going to do, but by the Angel she’d take some of them with her—

The gates of the courtyard burst open. They hadn’t been locked, but they were flung wide now with such force that despite their weight, they flew to the sides, slamming into the stone walls of the yard, rattling like sundered chains.

Beyond the gate was fog—thick and incongruous on such a sunny day. The violent tableau in the courtyard remained still, arrested in shock, as the fog cleared and a woman stepped into the yard.

She was slight and of medium height, her hair a deep brown, falling to her waist. She wore a torn shift over a long skirt that didn’t fit her well, and a pair of low boots. The bare skin of her arms and shoulders proclaimed her a Shadowhunter, with a Shadowhunter’s scars. The Voyance rune decorated her right hand.

She held no weapons. Instead she hugged a book to herself—an old volume, bound in dark leather, scuffed and worn. A folded piece of paper was stuck between two pages, like a bookmark. She raised her head and looked steadily before her at the scene in the courtyard; her expression was unsurprised, as if she’d expected nothing else.

Emma’s heart began to thump. She’d seen this woman before, though it had been a dark night in Cornwall. She knew her.

“I am Annabel Blackthorn.” The woman spoke in a clear, even tone, slightly accented. “The Black Volume is mine.”

Eochaid swore. He had a fine-boned, cruel face, like an eagle. “You lied to us,” he snarled at Emma and the rest. “You told us you had no idea where the book was.”

“Nor did they,” said Annabel, still with the same composure. “Malcolm Fade had it, and I took it from his dead body. But it is mine and always has been mine. It belonged in the library of the house I grew up in. The book has always been Blackthorn property.”