The Doors shuddered, then opened with a pleasant Ding!

Bob and his saber-toothed sidekick continued to weave around Tartarus’s legs, attacking, and dodging to stay out of his clutches. They didn’t seem to be doing much damage, but Tartarus lurched around, obviously not used to fighting in a humanoid body. He swiped and missed, swiped and missed.

More monsters surged toward the Doors. A spear flew past Annabeth’s head. She turned and stabbed an empousa through the gut, then dove for the Doors as they started to close.

She kept them open with her foot as she fought. At least with her back to the elevator car, she didn’t have to worry about attacks from behind.

“Percy, get over here!” she yelled.

He joined her in the doorway, his face dripping with sweat, and blood from several cuts.

“You okay?” she asked.

He nodded. “Got some kind of pain curse from that arai.” He hacked a gryphon out of the air. “Hurts, but it won’t kill me. Get in the elevator. I’ll hold the button.”

“Yeah, right!” She smacked a carnivorous horse in the snout with the butt of her sword and sent the monster stampeding through the crowd. “You promised, Seaweed Brain. We would not get separated! Ever again!”

“You’re impossible!”

“Love you too!”

An entire phalanx of Cyclopes charged forward, knocking smaller monsters out of the way. Annabeth figured she was about to die. “It had to be Cyclopes,” she grumbled.

Percy gave a battle cry. At the Cyclopes’ feet, a red vein in the ground burst open, spraying the monsters with liquid fire from the Phlegethon. The firewater might have healed mortals, but it didn’t do the Cyclopes any favors. They combusted in a tidal wave of heat. The burst vein sealed itself, but nothing remained of the monsters except a row of scorch marks.

“Annabeth, you have to go!” Percy said. “We can’t both stay!”

“No!” she cried. “Duck!”

He didn’t ask why. He crouched, and Annabeth vaulted over him, bringing her sword down on the head of a heavily tattooed ogre.

She and Percy stood shoulder to shoulder in the doorway, waiting for the next wave. The exploding vein had given the monsters pause, but it wouldn’t be long before they remembered: Hey, wait, there’s seventy-five gazillion of us, and only two of them.

“Well, then,” Percy said, “you have a better idea?”

Annabeth wished she did.

The Doors of Death stood right behind them—their exit from this nightmarish world. But they couldn’t use the Doors without someone manning the controls for twelve long minutes. If they stepped inside and let the Doors close without someone holding the button, Annabeth didn’t think the results would be healthy. And if they stepped away from the Doors for any reason, she imagined the elevator would close and disappear without them.

The situation was so pathetically sad, it was almost funny.

The crowd of monsters inched forward, snarling and gathering their courage.

Meanwhile, Bob’s attacks were getting slower. Tartarus was learning to control his new body. Saber-toothed Small Bob lunged at the god, but Tartarus smacked the cat sideways. Bob charged, bellowing with rage, but Tartarus grabbed his spear and yanked it out of his hands. He kicked Bob downhill, knocking over a row of telkhines like sea mammal bowling pins.

YIELD! Tartarus thundered.

“I will not,” Bob said. “You are not my master.”

Die in defiance, then, said the god of the pit. You Titans are nothing to me. My children the giants were always better, stronger, and more vicious. They will make the upper world as dark as my realm!

Tartarus snapped the spear in half. Bob wailed in agony. Saber-toothed Small Bob leaped to his aid, snarling at Tartarus and baring his fangs. The Titan struggled to rise, but Annabeth knew it was over. Even the monsters turned to watch, as if sensing that their master Tartarus was about to take the spotlight. The death of a Titan was worth seeing.

Percy gripped Annabeth’s hand. “Stay here. I’ve got to help him.”

“Percy, you can’t,” she croaked. “Tartarus can’t be fought. Not by us.”

She knew she was right. Tartarus was in a class by himself. He was more powerful than the gods or Titans. Demigods were nothing to him. If Percy charged to help Bob, he would get squashed like an ant.

But Annabeth also knew that Percy wouldn’t listen. He couldn’t leave Bob to die alone. That just wasn’t him—and that was one of the many reasons she loved him, even if he was an Olympian-sized pain in the podex.

“We’ll go together,” Annabeth decided, knowing this would be their final battle. If they stepped away from the Doors, they would never leave Tartarus. At least they would die fighting side by side.

She was about to say: Now.

A ripple of alarm passed through the army. In the distance, Annabeth heard shrieks, screams, and a persistent boom, boom, boom that was too fast to be the heartbeat in the ground—more like something large and heavy, running at full speed. An Earthborn spun into the air as if he’d been tossed. A plume of bright-green gas billowed across the top of the monstrous horde like the spray from a poison riot hose. Everything in its path dissolved.

Across the swath of sizzling, newly empty ground, Annabeth saw the cause of the commotion. She started to grin.

The Maeonian drakon spread its frilled collar and hissed, its poison breath filling the battlefield with the smell of pine and ginger. It shifted its hundred-foot-long body, flicking its dappled green tail and wiping out a battalion of ogres.

Riding on its back was a red-skinned giant with flowers in his rust-colored braids, a jerkin of green leather, and a drakon-rib lance in his hand.

“Damasen!” Annabeth cried.

The giant inclined his head. “Annabeth Chase, I took your advice. I chose myself a new fate.”

WHAT IS THIS? THE GOD OF THE PIT HISSED. Why have you come, my disgraced son?

Damasen glanced at Annabeth, a clear message in his eyes: Go. Now.

He turned toward Tartarus. The Maeonian drakon stamped its feet and snarled.

“Father, you wished for a more worthy opponent?” Damasen asked calmly. “I am one of the giants you are so proud of. You wished me to be more warlike? Perhaps I will start by destroying you!”

Damasen leveled his lance and charged.

The monstrous army swarmed him, but the Maeonian drakon flattened everything in its path, sweeping its tail and spraying poison while Damasen jabbed at Tartarus, forcing the god to retreat like a cornered lion.

Bob stumbled away from the battle, his saber-toothed cat at his side. Percy gave them as much cover as he could—causing blood vessels in the ground to burst one after the other. Some monsters were vaporized in Styx water. Others got a Cocytus shower and collapsed, weeping hopelessly. Others were doused with liquid Lethe and stared blankly around them, no longer sure where they were or even who they were.

Bob limped to the Doors. Golden ichor flowed from the wounds on his arms and chest. His janitor’s outfit hung in tatters. His posture was twisted and hunched, as if Tartarus’s breaking the spear had broken something inside him. Despite all that, he was grinning, his silver eyes bright with satisfaction.

“Go,” he ordered. “I will hold the button.”

Percy gawked at him. “Bob, you’re in no condition—”

“Percy.” Annabeth’s voice threatened to break. She hated herself for letting Bob do this, but she knew it was the only way. “We have to.”

“We can’t just leave them!”

“You must, friend.” Bob clapped Percy on the arm, nearly knocking him over. “I can still press a button. And I have a good cat to guard me.”

Small Bob the saber-toothed tiger growled in agreement.

“Besides,” Bob said, “it is your destiny to return to the world. Put an end to this madness of Gaea.”

A screaming Cyclops, sizzling from poison spray, sailed over their heads.

Fifty yards away, the Maeonian drakon trampled through monsters, its feet making sickening squish squish noises as if stomping grapes. On its back, Damasen yelled insults and jabbed at the god of the pit, taunting Tartarus farther away from the Doors.

Tartarus lumbered after him, his iron boots making craters in the ground.

You cannot kill me! he bellowed. I am the pit itself. You might as well try to kill the earth. Gaea and I—we are eternal. We own you, flesh and spirit!

He brought down his massive fist, but Damasen sidestepped, impaling his javelin in the side of Tartarus’s neck.

Tartarus growled, apparently more annoyed than hurt. He turned his swirling vacuum face toward the giant, but Damasen got out of the way in time. A dozen monsters were sucked into the vortex and disintegrated.

“Bob, don’t!” Percy said, his eyes pleading. “He’ll destroy you permanently. No coming back. No regeneration.”

Bob shrugged. “Who knows what will be? You must go now. Tartarus is right about one thing. We cannot defeat him. We can only buy you time.”

The Doors tried to close on Annabeth’s foot.

“Twelve minutes,” said the Titan. “I can give you that.”

“Percy…hold the Doors.” Annabeth jumped and threw her arms around the Titan’s neck. She kissed his cheek, her eyes so full of tears, she couldn’t see straight. Bob’s stubbly face smelled of cleaning supplies—fresh lemony furniture polish and Murphy Oil wood soap.

“Monsters are eternal,” she told him, trying to keep herself from sobbing. “We will remember you and Damasen as heroes, as the best Titan and the best giant. We’ll tell our children. We’ll keep the story alive. Someday, you will regenerate.”

Bob ruffled her hair. Smile lines crinkled around his eyes. “That is good. Until then, my friends, tell the sun and the stars hello for me. And be strong. This may not be the last sacrifice you must make to stop Gaea.”

He pushed her away gently. “No more time. Go.”

Annabeth grabbed Percy’s arm. She dragged him into the elevator car. She had one last glimpse of the Maeonian drakon shaking an ogre like a sock puppet, Damasen jabbing at Tartarus’s legs.

The god of the pit pointed at the Doors of Death and yelled: Monsters, stop them!

Small Bob the saber-toothed crouched and snarled, ready for action.

Bob winked at Annabeth. “Hold the Doors closed on your side,” he said. “They will resist your passage. Hold them—”

The panels slid shut.

“PERCY, HELP ME!” ANNABETH YELPED.

She shoved her entire body against the left door, pressing it toward the center. Percy did the same on the right. There were no handles, or anything else to hold on to. As the elevator car ascended, the Doors shook and tried to open, threatening to spill them into whatever was between life and death.

Annabeth’s shoulders ached. The elevator’s easy-listening music didn’t help. If all monsters had to hear that song about liking piña coladas and getting caught in the rain, no wonder they were in the mood for carnage when they reached the mortal world.

“We left Bob and Damasen,” Percy croaked. “They’ll die for us, and we just—”