Magnus cleared his throat. “I hate to bring this up, but we also can’t just leave Diyu in the hands of Sammael.”

“And Shinyun,” growled Alec.

“And Shinyun,” agreed Magnus.

“It just bothers me that we don’t know what Sammael wants,” said Clary in frustration.

“To come to Earth and wreak havoc there,” offered Alec.

“Yes, but to what end? Why open a Portal to Earth? What’s so great about Earth? If he only wanted to rule over Diyu, I think we would just let him.”

“Well, the food’s better on Earth,” Jace said.

Tian was shaking his head. “Sammael does not need a reason. The chaos and destruction he wreaks is for its own sake; who knows why his eye turns in one direction or another?”

“Sammael was slain by the Archangel Michael to prevent him from unleashing Hell on Earth,” said Magnus slowly. “He’ll want to do what he was prevented from doing so long ago, because it’s part of the war.”

“The war between angels and demons,” said Jace in a rare serious tone. “In which we are soldiers.”

“Right,” said Magnus. “One thing to remember about Princes of Hell, and archangels, too: they’re always playing nine-dimensional chess with worlds as their toys. Just assume the worst.”

“True enough,” said Tian. “The attack in the Market was a distraction, designed to keep the Shanghai Shadow World focused in one place so Sammael could act elsewhere. But we don’t know where.”

“We don’t know where in Shanghai,” said Alec. “But maybe we could figure out where in Diyu. He would pick some central location for his work, right? Not just some random torture chamber. And Shinyun and Ragnor would likely be with him.”

“You think we should confront them?” Jace asked. His eyes glittered. Only Jace would be looking forward to confronting two powerful warlocks and a Prince of Hell, thought Magnus.

“I think we’ll have better luck figuring out what’s going on closer to where they’re all acting—Sammael, Shinyun, and Ragnor—than we will out here in a bunch of abandoned courts,” said Alec.

“The geography of Diyu is complicated,” Tian said after a moment’s thought. “Though we are in an underworld, these courts we’re passing through actually reside far above the center of Diyu. There, a kind of shadow of the city of Shanghai can be found.”

“Like, it’s upside down?” said Clary.

“In part,” said Tian. “The usual rules of physical worlds don’t apply here. What is a mountain in Shanghai might be a deep trench in Diyu, but other places may be reversed in other ways, in color or orientation or even purpose. I was thinking…”

“That when I Tracked Ragnor, it led us to a spot in Shanghai where Ragnor wasn’t,” said Alec. “But maybe he’s in the mirror spot in Diyu? And maybe we can find that?”

“That’s very clever,” said Magnus. “My boyfriend is very clever,” he added, to no one in particular.

“Except we don’t really have a map that will show such correspondences,” said Tian. “We probably are best off heading for the heart of Diyu.” He grimaced. “As unpleasant as that will be.”

“What does heading for the heart of Diyu involve?” said Jace.

“The Final Court, but that won’t be a pleasant trip,” Tian said. “It’s at the center of Diyu’s labyrinth—the former throne of Yanluo. It’s at the very deepest point of Diyu, the lowest part of Hell.”

“Of course it is,” said Clary, sighing.

“Well, perhaps not the deepest. Below the Final Court is Avici.” Tian shuddered. “It is the one place in Diyu that terrifies me. Only the worst of sinners are brought there. Those who have committed one of the Great Offenses. Killing an angel, or a Buddha, or one’s own parent. They are judged and sent to Avici.”

It was probably Magnus’s imagination, but it seemed like Tian was looking straight at him. Alec was definitely looking straight at him, worry on his face. He knew well that Magnus had struck down his own stepfather—in self-defense, certainly, as he had been trying to kill Magnus, but Magnus didn’t know if Diyu cared about technicalities.

“How do we get there?” Magnus said. “The Final Court, I mean, not Avici.”

“Diyu is a maze of tens of thousands of hells,” said Tian. “If we try to find our way there through all those abandoned chambers, it could take the rest of our lives. But…” He trailed off, looking thoughtful.

“What?” said Alec.

“North of Shanghai,” said Tian, “south of Beijing, in Shandong Province, is Tai Shan—Mount Tai,” he clarified. “Thousands of years ago, it was a place of the dead. Now it’s a tourist attraction, but here in Diyu is its darkened mirror, a deep pit receding into shadow. I saw it on my return from the Bank of Sorrows. A road led down to it. I don’t know how far it would be, but perhaps deep enough to reach the shadow of Shanghai—”

“Well, it sounds better than wandering through a maze of torture chambers,” said Clary.

“Exactly,” said Tian with a smile.

They all looked at Magnus, who threw up his hands.

“I don’t have any better ideas,” he said. “I’m sorry you’ve all followed me into Hell again.”

Clary snorted. “It’s easier the second time.”

“It’s what we do,” said Jace. He went to retrieve his spear from where he’d left it leaning against the wall. “Lead the way.”

Alec didn’t look happy, but he nodded. “Let’s go.”

“I suggest we put on some Marks,” Tian said. “We will almost certainly be getting into some fights.”

“Marks work in Diyu?” Alec said, surprised.

“They do,” Tian confirmed, and Jace shrugged and took out his stele. Magnus had grown used to a lot of things about spending time with Shadowhunters, but the five solid minutes of drawing on one another that preceded every battle continued to be just a little bit funny to him every time.

“We leave by that side door,” Tian added, gesturing, and to Magnus he said, “Your friends are very casual about going where almost no living person has ever been.”

“Yeah,” said Magnus, “they’ve been through some stuff.”

* * *

THE PATH TOOK THEM OUT of the Second Court and into a walled passage. All of Magnus’s instincts had told him they were deep underground by this point, but the passage was lined at regular intervals with tall windows that looked out on a vast wasteland far below. The windows had once been elaborate carvings, with faces leering above them, but much of this had eroded away and crumbled.

As Tian, Jace, and Clary went ahead, Magnus hung back to join Alec. “You don’t like it,” he said. “The plan, I mean. Too vague?”

“No. I mean, it’s vague, but I agree we should get to where the action is. And where the Book of the White is. If we can get it away from Ragnor and the others, we can maybe wreck Sammael’s plan.”

“Or at least ruin his day. You think he’s using the Book to figure out how to break through from Diyu to Earth?” said Magnus. It was the same thought he’d had.

Alec nodded.

“Are you angry with me?” said Magnus.

“What?” Alec said sharply.

Magnus stopped walking. “It’s just—you’re all here because of me. If I hadn’t lost the Book of the White… if I hadn’t been caught by surprise by Ragnor…”

Alec snorted. “If I hadn’t been in the shower.”

“It’s not the same,” Magnus said. “I shouldn’t have kept the Book in Max’s room. I should’ve been more careful about the wards on the apartment.”

“Magnus,” Alec said, and he put his hand on Magnus’s cheek. He looked into Magnus’s eyes, and feeling the strange power of the thorn bubbling within him, Magnus wondered what he saw there. “Given that one of the minions of the Father of Demons was holding our kid, and that kid ended up safe in bed at the end of it, from my perspective you handled things perfectly. I’m not angry at you.” He sighed. “I’m kind of angry at Isabelle, so let’s go rescue her before something terrible happens to her.”

“No pressure,” said Magnus.

“Yeah,” said Alec. “That’s why I’m kind of angry at her. Because I hate worrying about someone I love. But I’m not angry at you,” he said again. “Clary’s right and Jace is right. I’m your partner. They’re your friends. We’ve followed you into Hell before, and we’re doing it again, and we would do it a third time.

“Besides,” he added with a smile, “a Prince of Hell trying to break through to our world is absolutely our jurisdiction.”

He leaned forward and kissed Magnus, gently, slowly, the way he would on a Sunday morning in bed. It was totally at odds with their situation, totally at odds with how either of them felt in that moment. It was wonderful.

“Not the time!” Jace yelled from a little ways ahead of them.

“Always the time,” Alec murmured against Magnus’s mouth. He called back to Jace, “Just working to keep up morale!”

They hurried to catch up with the others. Magnus felt a little better about Alec, but the uncertainty of where they were going and what they would do there remained in the bottom of his gut like a jagged stone.

And then they saw the pit of Mount Tai.

As they came around a wide curve in the passage, the walls fell away and suddenly they were walking through a wasteland. From their passage, a wide, black ribbon of road jutted off to one side, winding through a blasted wilderness of rock and ruin. In the distance, it glittered darkly—an upside-down mountain, just as Tian had said. Stark, black even against the constant gray background of Diyu, a yawning chasm in the distance that seemed to split open the land.