“Yeah. You’ll have to trust me. Put your arms around my neck and hang on.”

“How can you possibly—”

“There!” cried a voice behind them. “Kill the ungrateful tourists!”

The children of Nyx had found them. Annabeth wrapped her arms around Percy’s neck. “Go!”

With her eyes closed, she could only guess how he managed it. Maybe he used the force of the river somehow. Maybe he was just scared out of his mind and charged with adrenaline. Percy leaped with more strength than she would have thought possible. They sailed through the air as the river churned and wailed below them, splashing Annabeth’s bare ankles with stinging brine.

Then—CLUMP. They were on solid ground again.

“You can open your eyes,” Percy said, breathing hard. “But you won’t like what you see.”

Annabeth blinked. After the darkness of Nyx, even the dim red glow of Tartarus seemed blinding.

Before them stretched a valley big enough to fit the San Francisco Bay. The booming noise came from the entire landscape, as if thunder were echoing from beneath the ground. Under poisonous clouds, the rolling terrain glistened purple with dark red and blue scar lines.

“It looks like…” Annabeth fought down her revulsion. “Like a giant heart.”

“The heart of Tartarus,” Percy murmured.

The center of the valley was covered with a fine black fuzz of peppery dots. They were so far away, it took Annabeth a moment to realize she was looking at an army—thousands, maybe tens of thousands of monsters, gathered around a central pinpoint of darkness. It was too far to see any details, but Annabeth had no doubt what the pinpoint was. Even from the edge of the valley, Annabeth could feel its power tugging at her soul.

“The Doors of Death.”

“Yeah.” Percy’s voice was hoarse. He still had the pale, wasted complexion of a corpse…which meant he looked about as good as Annabeth felt.

She realized she’d forgotten all about their pursuers. “What happened to Nyx…?”

She turned. Somehow they’d landed several hundred yards from the banks of Acheron, which flowed through a channel cut into black volcanic hills. Beyond that was nothing but darkness.

No sign of anyone coming after them. Apparently even the minions of Night didn’t like to cross the Acheron.

She was about to ask Percy how he had jumped so far when she heard the skittering of a rockslide in the hills to their left. She drew her drakon-bone sword. Percy raised Riptide.

A patch of glowing white hair appeared over the ridge, then a familiar grinning face with pure silver eyes.

“Bob?” Annabeth was so happy she actually jumped. “Oh my gods!”

“Friends!” The Titan lumbered toward them. The bristles of his broom had been burned off. His janitor’s uniform was slashed with new claw marks, but he looked delighted. On his shoulder, Small Bob the kitten purred almost as loudly as the pulsing heart of Tartarus.

“I found you!” Bob gathered them both in a rib-crushing hug. “You look like smoking dead people. That is good!”

“Urf,” Percy said. “How did you get here? Through the Mansion of Night?”

“No, no.” Bob shook his head adamantly. “That place is too scary. Another way—only good for Titans and such.”

“Let me guess,” Annabeth said. “You went sideways.”

Bob scratched his chin, evidently at a loss for words. “Hmm. No. More…diagonal.”

Annabeth laughed. Here they were at the heart of Tartarus, facing an impossible army—she would take any comfort she could get. She was ridiculously glad to have Bob the Titan with them again.

She kissed his immortal nose, which made him blink.

“We stay together now?” he asked.

“Yes,” Annabeth agreed. “Time to see if this Death Mist works.”

“And if it doesn’t…” Percy stopped himself.

There was no point in wondering about that. They were about to march into the middle of an enemy army. If they were spotted, they were dead.

Despite that, Annabeth managed a smile. Their goal was in sight. They had a Titan with a broom and a very loud kitten on their side. That had to count for something.

“Doors of Death,” she said, “here we come.”

JASON WASN’T SURE WHAT TO HOPE FOR: storm or fire.

As he waited for his daily audience with the lord of the South Wind, he tried to decide which of the god’s personalities, Roman or Greek, was worse. But after five days in the palace, he was only certain about one thing: he and his crew were unlikely to get out of here alive.

He leaned against the balcony rail. The air was so hot and dry, it sucked the moisture right out of his lungs. Over the last week, his skin had gotten darker. His hair had turned as white as corn silk. Whenever he glanced in the mirror, he was startled by the wild, empty look in his eyes, as if he’d gone blind wandering in the desert.

A hundred feet below, the bay glittered against a crescent of red sand beach. They were somewhere on the northern coast of Africa. That’s as much as the wind spirits would tell him.

The palace itself stretched out on either side of him—a honeycomb of halls and tunnels, balconies, colonnades, and cavernous rooms carved into the sandstone cliffs, all designed for the wind to blow through and make as much noise as possible. The constant pipe-organ sounds reminded Jason of the floating lair of Aeolus, back in Colorado, except here the winds seemed in no hurry.

Which was part of the problem.

On their best days, the southern venti were slow and lazy. On their worst days, they were gusty and angry. They’d initially welcomed the Argo II, since any enemy of Boreas was a friend of the South Wind, but they seemed to have forgotten that the demigods were their guests. The venti had quickly lost interest in helping repair the ship. Their king’s mood got worse every day.

Down at the dock, Jason’s friends were working on the Argo II. The main sail had been repaired, the rigging replaced. Now they were mending the oars. Without Leo, they were unable to repair the more complicated parts of the ship, even with the help of Buford the table and Festus (who was now permanently activated thanks to Piper’s charmspeak—and none of them understood that). But they kept trying.

Hazel and Frank stood at the helm, tinkering with the controls. Piper relayed their commands to Coach Hedge, who was hanging over the side of the ship, banging out dents in the oars. Hedge was well suited for banging on things.

They didn’t seem to be making much progress, but considering what they’d been through, it was a miracle the ship was in one piece.

Jason shivered when he thought about Khione’s attack. He’d been rendered helpless—frozen solid not once but twice, while Leo was blasted into the sky and Piper was forced to save them all single-handedly.

Thank the gods for Piper. She considered herself a failure for not having stopped the wind bomb from exploding; but the truth was, she’d saved the entire crew from becoming ice sculptures in Quebec.

She’d also managed to direct the explosion of the icy sphere, so even though the ship had been pushed halfway across the Mediterranean, it had sustained relatively minor damage.

Down at the dock, Hedge yelled, “Try it now!”

Hazel and Frank pulled some of the levers. The port oars went crazy, chopping up and down and doing the wave. Coach Hedge tried to dodge, but one smacked him in the rear and launched him into the air. He came down screaming and splashed into the bay.

Jason sighed. At this rate, they’d never be able to sail, even if the southern venti allowed them to. Somewhere in the north, Reyna was flying toward Epirus, assuming she’d gotten his note at Diocletian’s Palace. Leo was lost and in trouble. Percy and Annabeth…well, best-case scenario they were still alive, making their way to the Doors of Death. Jason couldn’t let them down.

A rustling sound made him turn. Nico di Angelo stood in the shadow of the nearest column. He’d shed his jacket. Now he just wore his black T-shirt and black jeans. His sword and the scepter of Diocletian hung on either side of his belt.

Days in the hot sun hadn’t tanned his skin. If anything, he looked paler. His dark hair fell over his eyes. His face was still gaunt, but he was definitely in better shape than when they’d left Croatia. He had regained enough weight not to look starved. His arms were surprisingly taut with muscles, as if he’d spent the past week sword fighting. For all Jason knew, he’d been slipping off to practice raising spirits with Diocletian’s scepter, then sparring with them. After their expedition in Split, nothing would surprise him.

“Any word from the king?” Nico asked.

Jason shook his head. “Every day, he calls for me later and later.”

“We need to leave,” Nico said. “Soon.”

Jason had been having the same feeling, but hearing Nico say it made him even edgier. “You sense something?”

“Percy is close to the Doors,” Nico said. “He’ll need us if he’s going to make it through alive.”

Jason noticed that he didn’t mention Annabeth. He decided not to bring that up.

“All right,” Jason said. “But if we can’t repair the ship—”

“I promised I’d lead you to the House of Hades,” Nico said. “One way or another, I will.”

“You can’t shadow-travel with all of us. And it will take all of us to reach the Doors of Death.”

The orb at the end of Diocletian’s scepter glowed purple. Over the past week, it seemed to have aligned itself to Nico di Angelo’s moods. Jason wasn’t sure that was a good thing.

“Then you’ve got to convince the king of the South Wind to help.” Nico’s voice seethed with anger. “I didn’t come all this way, suffer so many humiliations…”

Jason had to make a conscious effort not to reach for his sword. Whenever Nico got angry, all of Jason’s instincts screamed, Danger!

“Look, Nico,” he said, “I’m here if you want to talk about, you know, what happened in Croatia. I get how difficult—”

“You don’t get anything.”

“Nobody’s going to judge you.”

Nico’s mouth twisted in a sneer. “Really? That would be a first. I’m the son of Hades, Jason. I might as well be covered in blood or sewage, the way people treat me. I don’t belong anywhere. I’m not even from this century. But even that’s not enough to set me apart. I’ve got to be—to be—”

“Dude! It’s not like you’ve got a choice. It’s just who you are.”

“Just who I am…” The balcony trembled. Patterns shifted in the stone floor, like bones coming to the surface. “Easy for you to say. You’re everybody’s golden boy, the son of Jupiter. The only person who ever accepted me was Bianca, and she died! I didn’t choose any of this. My father, my feelings…”

Jason tried to think of something to say. He wanted to be Nico’s friend. He knew that was the only way to help. But Nico wasn’t making it easy.

He raised his hands in submission. “Yeah, okay. But, Nico, you do choose how to live your life. You want to trust somebody? Maybe take a risk that I’m really your friend and I’ll accept you. It’s better than hiding.”