Magnus hesitated. “I am a man of many talents, but swordplay is definitely not one of them.”

“And I tell you, when it comes time, you won’t need to kill with them,” said Gan Jiang. He examined the group with narrowed eyes. “These are swords of mercy and judgment. You, warlock, must take mercy, the white blade—” Mo Ye picked up White Impermanence and went behind Magnus, where she began fussily fastening it to his back with a strap and sheath. Alec smiled at Magnus, who had immediately adopted the neutral expression he wore when a tailor was pinning his clothes for alteration.

“And you, Nephilim, will carry the black.” Gan Jiang offered Black Impermanence’s hilt to Alec.

Alec was about to say, Why do I have to be “judgment”? but the moment his hand gripped the sword, the room and the smiths and his friends vanished, and he was in a different place.

A featureless cracked plain, black and pitted, extended forever to an empty horizon. Above it stretched a red sky, hung with a sun too large and dark as blood.

On the plain was Magnus. Or whatever Magnus had become.

He had not become a monster, not really. He didn’t look more like an animal, or a demon. But he had grown to a terrifying height, and when he looked down at Alec, it was with whited-out eyes and no recognition.

This huge Magnus brought his bare arms up, and Alec could see iron chains, affixed to a spiked ball punched through each of his palms. The chains receded behind Magnus into a storm of smoke and flame that trailed behind him.

Magnus still had the freedom of movement to bring his hands together. Jagged, gleaming shards of pinkish-red magic began to coalesce between his hands, and Alec could feel the ground rumble and the power begin to gather.

He held the Black Impermanence before him, and he understood beyond any doubt that only he could wield it. Only he could make the judgment, if it came to it. If Magnus was overcome by the thorn, by Sammael.

Also, the thought of this version of Magnus, all emotion absent, burning with power, wielding a sword of judgment, was a little terrifying.

He held the sword before him, pointing it toward the dark god that had been Magnus, and he said, “Magnus, if you know me, speak to me.”

Then he was back in the stone room. Gan Jiang was watching him keenly.

“Obviously I know you,” Magnus said worriedly. “Are you all right?”

Alec looked at Gan Jiang, and he nodded. “He’s fine,” he said. “Bit of a moment with the sword, I think.”

“I think your husband’s been tested,” Mo Ye said brightly to Magnus. “Good news! He passed.”

Magnus looked at Alec with concern.

Alec felt himself blush. “We’re not married,” he said apologetically as he strapped the sword to his back.

“You’re not married yet,” Isabelle piped up.

Gan Jiang laughed. “Do you see rings on our hands? And yet Mo Ye and I have been married since before the sea was salt.” He leaned into Alec. “Stay with him,” he said in a confidential tone.

“I plan to,” said Alec.

“Excellent!” Gan Jiang barked. “Now, you must go. We are closing for supper.”

This was so abrupt that they all stood around dumbly for a moment.

“You don’t have ears?” Mo Ye said. “Get out! We’re closed! You’re needed in the Market!”

They hustled Magnus and the Shadowhunters out of the room and back onto the street. Somehow, in the short time that they had been inside the faerie smithy, the sun had dropped below the buildings, and it was full dusk. An orange glow passed over the buildings and the trees, and a warm breeze blew gently, carrying the scent of flowers and of the food stalls at the Market nearby.

The door slammed shut, and Alec heard the sound of several latches and bolts being thrown.

“That was surprisingly similar to visiting my grandparents,” Simon said after a moment. “Except they would have fed us.”

“What happened in there, Alec?” Jace said.

“I had a vision,” Alec said slowly.

“A vision of what?” said Isabelle.

“Of what would happen if we fail to stop Sammael, I think.”

Jace said, “Did it give you any insight? Into what we should do?”

Alec was looking at Magnus. “Not fail.”

“All right,” said Jace. “We’ve got research, we’ve got swords. What’s our next step?”

“Signs are pointing toward us needing to know more about Diyu,” said Isabelle. “We could start checking the possible locations for the old Portal. What do you think, Tian?… Tian?”

They all looked around. Tian had definitely been in the smithy with them, but he was gone. Alec realized he hadn’t seen the young Shadowhunter since before they had taken the swords.

There was a burst of light from the sky above the central Market square. A purple afterimage flashed in Alec’s eyes, and he blinked, trying to clear it. Not far away, someone began to scream.

* * *

THEY WERE BARELY ARMED. THEY weren’t wearing gear. They hadn’t applied combat runes. Magnus had one of their two swords, and he hadn’t swung a sword in decades. In fact, he could barely figure out how to untangle it from the complicated shoulder harness Mo Ye had strapped to his back.

But they all ran toward the Market square anyway.

The place was chaos. Downworlders ran helter-skelter in all directions, looking for refuge or escape. Market stall grates and shutters slammed closed. Silhouettes scattered in the dim light; Magnus could hardly tell what was happening on the ground. Far above them, a blackish glow throbbed, like a circle cut out of the sky. It was almost the size of the square itself. And out of the circle came demons.

“It’s a Portal,” said Isabelle, her black hair whipping in the wind.

“A dimensional Portal,” yelled Clary, over the sound of chaos. “Not a normal one—this one goes to another world—”

Diyu. They all knew it without saying the word, even before Ragnor and Shinyun stepped free of the Portal and hovered in the air before them, their arms raised and red magic crackling between them. It was the same color that Magnus’s magic had become.

Magnus looked up at the Portal. He could see nothing through it, only clouds so dark they were almost black. Long silken threads were emerging from points within it, and down those threads slid dark gray spheres the size of large dogs. As they descended, they unfolded to reveal themselves to be—no surprise, given the day he’d had—huge spiders.

He shot Alec a glance. Alec wasn’t the biggest fan of spiders, and Magnus had grown entertained by his unwillingness to deal with even small ones that showed up in their loft, despite also being a heavily armed angelic warrior.

Now Alec drew Black Impermanence and gritted his teeth. “Let’s see how well this god-key works as a plain old sword.”

Magnus began gathering magic between his hands, disturbed that it was the same color as their enemies’. He was distracted by Ragnor’s deep voice, carrying above the chaos. “The host of Diyu is upon you! The courts have judged you unworthy, and you will suffer the tortures of the dead!”

Simon was frozen, gazing in horror at the spiders descending. Behind them, streams of fog announced the arrival of Ala demons, who swooped down, screaming, to chase Downworlders through the narrow passages of the Market. A pack of hellhounds had appeared and cornered a pixie family. Magnus was about to call out for Simon when Jace ran past him, carrying two of the curved-head pikes from the fence outside the smithy, one in each hand.

“Heads up, Lewis! Sorry, Lovelace!” he yelled, and Simon jerked out of his daze just in time to catch one of the spears. He appeared to take a moment to gather himself, and then he and Jace rushed the hellhounds together. One hellhound let a child fall from its jaws as Jace’s spear bit into its side. The demonic dog yelped and crashed to the ground; the rest of the hounds turned to face them, eyes red and jaws open, baring rows of jagged fangs.

The lead hellhound went down, felled by Simon. Another hound roared and leaped for Jace, who neatly ducked and used the spear handle and the hound’s own momentum to send it crashing through a window.

Xiangliu began to swarm toward Jace and Simon, but Clary quickly appeared to cover them. She lashed out with a glowing seraph blade, whirling around, a blur of light in the fog. In a moment of pause she caught Magnus’s eye, then looked up at the warlocks above. Magnus understood her meaning—he had to fly up there and engage with them, just as he had in front of the Institute. In this fight, though, nobody had a bow, and he would be exposed in the air, protected only by his own magic.

Isabelle, meanwhile, had gotten pushed back toward a striped canvas tent by a group of the spider demons. She had only a single seraph blade and no parabatai to keep an eye on her. The spiders, sensing her to be vulnerable, leaped. Isabelle spun and kicked one out of the air, but doing so unbalanced her, and she went tumbling back into the tent, which collapsed around her and the spiders.

Magnus cried out and ran toward her, but he needn’t have worried. The body of one of the spider demons suddenly emerged from the mess, impaled like a kebab on the end of a steel strut, part of the structure of the collapsed tent. Isabelle appeared, wielding the strut like a quarterstaff, and knocked two more spiders away. Now she held it ahead of her, keeping the spiders at bay, and with her free hand plucked her seraph blade from its sheath and yelled, “Nuriel!”

The seraph blade blazed. Isabelle spun and turned the attack on the spiders, pushing them back, when Alec appeared, slicing away with Black Impermanence. Ichor flew.

Shinyun landed amid the demons and produced a massive fireball, which she hurled at Jace, Clary, and Simon, who were fighting back-to-back. Magnus, without thinking, flung himself between the fireball and his friends, and the blazing orb smashed into him, where it disappeared, seeming to sink into his chest. Clary saw and her eyes widened.

“Why are you doing this?” Magnus yelled at Shinyun. “These are Downworlders! They are your people!”

Shinyun turned her impassive gaze upon him. “Witness,” she called out, “the opening of a new, permanent path to Diyu!” She drew her hand down, trailing pink flame, and more of the spider demons sprang from her fingers. “Zhizhu-jing, my sisters! This is your world now! Prepare the way for your new master!”