Still, this wasn’t fair. She’d gone through so much to retrieve that statue of Athena. Just when she’d succeeded, when things had been looking up and she’d been reunited with Percy, they had plunged to their deaths.

Even the gods couldn’t devise a fate so twisted.

But Gaea wasn’t like other gods. The Earth Mother was older, more vicious, more bloodthirsty. Annabeth could imagine her laughing as they fell into the depths.

Annabeth pressed her lips to Percy’s ear. “I love you.”

She wasn’t sure he could hear her—but if they were going to die she wanted those to be her last words.

She tried desperately to think of a plan to save them. She was a daughter of Athena. She’d proven herself in the tunnels under Rome, beaten a whole series of challenges with only her wits. But she couldn’t think of any way to reverse or even slow their fall.

Neither of them had the power to fly—not like Jason, who could control the wind, or Frank, who could turn into a winged animal. If they reached the bottom at terminal velocity…well, she knew enough science to know it would be terminal.

She was seriously wondering whether they could fashion a parachute out of their shirts—that’s how desperate she was—when something about their surroundings changed. The darkness took on a gray-red tinge. She realized she could see Percy’s hair as she hugged him. The whistling in her ears turned into more of a roar. The air became intolerably hot, permeated with a smell like rotten eggs.

Suddenly, the chute they’d been falling through opened into a vast cavern. Maybe half a mile below them, Annabeth could see the bottom. For a moment she was too stunned to think properly. The entire island of Manhattan could have fit inside this cavern—and she couldn’t even see its full extent. Red clouds hung in the air like vaporized blood. The landscape—at least what she could see of it—was rocky black plains, punctuated by jagged mountains and fiery chasms. To Annabeth’s left, the ground dropped off in a series of cliffs, like colossal steps leading deeper into the abyss.

The stench of sulfur made it hard to concentrate, but she focused on the ground directly below them and saw a ribbon of glittering black liquid—a river.

“Percy!” she yelled in his ear. “Water!”

She gestured frantically. Percy’s face was hard to read in the dim red light. He looked shell-shocked and terrified, but he nodded as if he understood.

Percy could control water—assuming that was water below them. He might be able to cushion their fall somehow. Of course Annabeth had heard horrible stories about the rivers of the Underworld. They could take away your memories, or burn your body and soul to ashes. But she decided not to think about that. This was their only chance.

The river hurtled toward them. At the last second, Percy yelled defiantly. The water erupted in a massive geyser and swallowed them whole.

THE IMPACT DIDN’T KILL HER, but the cold nearly did.

Freezing water shocked the air right out of her lungs. Her limbs turned rigid, and she lost her grip on Percy. She began to sink. Strange wailing sounds filled her ears—millions of heartbroken voices, as if the river were made of distilled sadness. The voices were worse than the cold. They weighed her down and made her numb.

What’s the point of struggling? they told her. You’re dead anyway. You’ll never leave this place.

She could sink to the bottom and drown, let the river carry her body away. That would be easier. She could just close her eyes.…

Percy gripped her hand and jolted her back to reality. She couldn’t see him in the murky water, but suddenly she didn’t want to die. Together they kicked upward and broke the surface.

Annabeth gasped, grateful for the air, no matter how sulfurous. The water swirled around them, and she realized Percy was creating a whirlpool to buoy them up.

Though she couldn’t make out their surroundings, she knew this was a river. Rivers had shores.

“Land,” she croaked. “Go sideways.”

Percy looked near dead with exhaustion. Usually water reinvigorated him, but not this water. Controlling it must have taken every bit of his strength. The whirlpool began to dissipate. Annabeth hooked one arm around his waist and struggled across the current. The river worked against her: thousands of weeping voices whispering in her ears, getting inside her brain.

Life is despair, they said. Everything is pointless, and then you die.

“Pointless,” Percy murmured. His teeth chattered from the cold. He stopped swimming and began to sink.

“Percy!” she shrieked. “The river is messing with your mind. It’s the Cocytus—the River of Lamentation. It’s made of pure misery!”

“Misery,” he agreed.

“Fight it!”

She kicked and struggled, trying to keep both of them afloat. Another cosmic joke for Gaea to laugh at: Annabeth dies trying to keep her boyfriend, the son of Poseidon, from drowning.

Not going to happen, you hag, Annabeth thought.

She hugged Percy tighter and kissed him. “Tell me about New Rome,” she demanded. “What were your plans for us?”

“New Rome…For us…”

“Yeah, Seaweed Brain. You said we could have a future there! Tell me!”

Annabeth had never wanted to leave Camp Half-Blood. It was the only real home she’d ever known. But days ago, on the Argo II, Percy had told her that he imagined a future for the two of them among the Roman demigods. In their city of New Rome, veterans of the legion could settle down safely, go to college, get married, even have kids.

“Architecture,” Percy murmured. The fog started to clear from his eyes. “Thought you’d like the houses, the parks. There’s one street with all these cool fountains.”

Annabeth started making progress against the current. Her limbs felt like bags of wet sand, but Percy was helping her now. She could see the dark line of the shore about a stone’s throw away.

“College,” she gasped. “Could we go there together?”

“Y-yeah,” he agreed, a little more confidently.

“What would you study, Percy?”

“Dunno,” he admitted.

“Marine science,” she suggested. “Oceanography?”

“Surfing?” he asked.

She laughed, and the sound sent a shock wave through the water. The wailing faded to background noise. Annabeth wondered if anyone had ever laughed in Tartarus before—just a pure, simple laugh of pleasure. She doubted it.

She used the last of her strength to reach the riverbank. Her feet dug into the sandy bottom. She and Percy hauled themselves ashore, shivering and gasping, and collapsed on the dark sand.

Annabeth wanted to curl up next to Percy and go to sleep. She wanted to shut her eyes, hope all of this was just a bad dream, and wake up to find herself back on the Argo II, safe with her friends (well…as safe as a demigod can ever be).

But, no. They were really in Tartarus. At their feet, the River Cocytus roared past, a flood of liquid wretchedness. The sulfurous air stung Annabeth’s lungs and prickled her skin. When she looked at her arms, she saw they were already covered with an angry rash. She tried to sit up and gasped in pain.

The beach wasn’t sand. They were sitting on a field of jagged black-glass chips, some of which were now embedded in Annabeth’s palms.

So the air was acid. The water was misery. The ground was broken glass. Everything here was designed to hurt and kill. Annabeth took a rattling breath and wondered if the voices in the Cocytus were right. Maybe fighting for survival was pointless. They would be dead within the hour.

Next to her, Percy coughed. “This place smells like my ex-stepfather.”

Annabeth managed a weak smile. She’d never met Smelly Gabe, but she’d heard enough stories. She loved Percy for trying to lift her spirits.

If she’d fallen into Tartarus by herself, Annabeth thought, she would have been doomed. After all she’d been through beneath Rome, finding the Athena Parthenos, this was simply too much. She would’ve curled up and cried until she became another ghost, melting into the Cocytus.

But she wasn’t alone. She had Percy. And that meant she couldn’t give up.

She forced herself to take stock. Her foot was still wrapped in its makeshift cast of board and Bubble Wrap, still tangled in cobwebs. But when she moved it, it didn’t hurt. The ambrosia she’d eaten in the tunnels under Rome must have finally mended her bones.

Her backpack was gone—lost during the fall, or maybe washed away in the river. She hated losing Daedalus’s laptop, with all its fantastic programs and data, but she had worse problems. Her Celestial bronze dagger was missing—the weapon she’d carried since she was seven years old.

The realization almost broke her, but she couldn’t let herself dwell on it. Time to grieve later. What else did they have?

No food, no water…basically no supplies at all.

Yep. Off to a promising start.

Annabeth glanced at Percy. He looked pretty bad. His dark hair was plastered across his forehead, his T-shirt ripped to shreds. His fingers were scraped raw from holding on to that ledge before they fell. Most worrisome of all, he was shivering and his lips were blue.

“We should keep moving or we’ll get hypothermia,” Annabeth said. “Can you stand?”

He nodded. They both struggled to their feet.

Annabeth put her arm around his waist, though she wasn’t sure who was supporting whom. She scanned their surroundings. Above, she saw no sign of the tunnel they’d fallen down. She couldn’t even see the cavern roof—just blood-colored clouds floating in the hazy gray air. It was like staring through a thin mix of tomato soup and cement.

The black-glass beach stretched inland about fifty yards, then dropped off the edge of a cliff. From where she stood, Annabeth couldn’t see what was below, but the edge flickered with red light as if illuminated by huge fires.

A distant memory tugged at her—something about Tartarus and fire. Before she could think too much about it, Percy inhaled sharply.

“Look.” He pointed downstream.

A hundred feet away, a familiar-looking baby-blue Italian car had crashed headfirst into the sand. It looked just like the Fiat that had smashed into Arachne and sent her plummeting into the pit.

Annabeth hoped she was wrong, but how many Italian sports cars could there be in Tartarus? Part of her didn’t want to go anywhere near it, but she had to find out. She gripped Percy’s hand, and they stumbled toward the wreckage. One of the car’s tires had come off and was floating in a backwater eddy of the Cocytus. The Fiat’s windows had shattered, sending brighter glass like frosting across the dark beach. Under the crushed hood lay the tattered, glistening remains of a giant silk cocoon—the trap that Annabeth had tricked Arachne into weaving. It was unmistakably empty. Slash marks in the sand made a trail downriver…as if something heavy, with multiple legs, had scuttled into the darkness.

“She’s alive.” Annabeth was so horrified, so outraged by the unfairness of it all, she had to suppress the urge to throw up.

“It’s Tartarus,” Percy said. “Monster home court. Down here, maybe they can’t be killed.”