The sky turned dark and cold. Shadows thickened. A harsh war horn sounded, and as the dead soldiers formed up ranks with their guns and swords and spears, an enormous chariot roared down Fifth Avenue. It came to a stop next to Nico. The horses were living shadows, fashioned from darkness. The chariot was inlaid with obsidian and gold, decorated with scenes of painful death. Holding the reins was Hades himself, Lord of the Dead, with Demeter and Persephone riding behind him.

Hades wore black armor and a cloak the color of fresh blood. On top of his pale head was the helm of darkness: a crown that radiated pure terror. It changed shape as I watched—from a dragon's head to a circle of black flames to a wreath of human bones. But that wasn't the scary part. The helm reached into my mind and ignited my worst nightmares, my most secret fears. I wanted to crawl into a hole and hide, and I could tell the enemy army felt the same way. Only Kronos's power and authority kept his ranks from fleeing.

Hades smiled coldly. "Hello, Father. You're looking . . . young."

"Hades," Kronos growled. "I hope you and the ladies have come to pledge your allegiance."

"I'm afraid not." Hades sighed. "My son here convinced me that perhaps I should prioritize my list of enemies." He glanced at me with distaste. "As much as I dislike certain upstart demigods, it would not do for Olympus to fall. I would miss bickering with my siblings. And if there is one thing we agree on—it is that you were a TERRIBLE father."

"True," muttered Demeter. "No appreciation of agriculture."

"Mother!" Persephone complained.

Hades drew his sword, a double-edged Stygian blade etched with silver. "Now fight me! For today the House of Hades will be called the saviors of Olympus."

"I don't have time for this," Kronos snarled.

He struck the ground with his scythe. A crack spread in both directions, circling the Empire State Building. A wall of force shimmered along the fissure line, separating Kronos's vanguard, my friends, and me from the bulk of the two armies.

"What's he doing?" I muttered.

"Sealing us in," Thalia said. "He's collapsing the magic barriers around Manhattan—cutting off just the building, and us."

Sure enough, outside the barrier, car engines revved to life. Pedestrians woke up and stared uncomprehendingly at the monsters and zombies all around them. No telling what they saw through the Mist, but I'm sure it was plenty scary. Car doors opened. And at the end of the block, Paul Blofis and my mom got out of their Prius.

"No," I said. "Don't . . ."

My mother could see through the Mist. I could tell from her expression that she understood how serious things were. I hoped she would have the sense to run. But she locked eyes with me, said something to Paul, and they ran straight toward us.

I couldn't call out. The last thing I wanted to do was bring her to Kronos's attention.

Fortunately, Hades caused a distraction. He charged at the wall of force, but his chariot crashed against it and overturned. He got to his feet, cursing, and blasted the wall with black energy. The barrier held.

"ATTACK!" he roared.

The armies of the dead clashed with the Titan's monsters. Fifth Avenue exploded into absolute chaos. Mortals screamed and ran for cover. Demeter waved her hand and an entire column of giants turned into a wheat field. Persephone changed the dracaenae's spears into sunflowers. Nico slashed and hacked his way through the enemy, trying to protect the pedestrians as best he could. My parents ran toward me, dodging monsters and zombies, but there was nothing I could do to help them.

"Nakamura," Kronos said. "Attend me. Giants—deal with them."

He pointed at my friends and me. Then he ducked into the lobby.

For a second I was stunned. I'd been expecting a fight, but Kronos completely ignored me like I wasn't worth the trouble. That made me mad.

The first Hyperborean giant smashed at me with his club. I rolled between his legs and stabbed Riptide into his backside. He shattered into a pile of ice shards. The second giant breathed frost at Annabeth, who was barely able to stand, but Grover pulled her out of the way while Thalia went to work. She sprinted up the giant's back like a gazelle, sliced her hunting knives across his monstrous blue neck, and created the world's largest headless ice sculpture.

I glanced outside the magic barrier. Nico was fighting his way toward my mom and Paul, but they weren't waiting for help. Paul grabbed a sword from a fallen hero and did a pretty fine job keeping a dracaena busy. He stabbed her in the gut, and she disintegrated.

"Paul?" I said in amazement.

He turned toward me and grinned. "I hope that was a monster I just killed. I was a Shakespearian actor in college! Picked up a little swordplay!"

I liked him even better for that, but then a Laistrygonian giant charged toward my mom. She was rummaging around in an abandoned police car—maybe looking for the emergency radio—and her back was turned.

"Mom!" I yelled.

She whirled when the monster was almost on top of her. I thought the thing in her hands was an umbrella until she cranked the pump and the shotgun blast blew the giant twenty feet backward, right into Nico's sword.

"Nice one," Paul said.

"When did you learn to fire a shotgun?" I demanded.

My mom blew the hair out of her face. "About two seconds ago. Percy, we'll be fine. Go!"

"Yes," Nico agreed, "we'll handle the army. You have to get Kronos!"

"Come on, Seaweed Brain!" Annabeth said. I nodded. Then I looked at the rubble pile on the side of the building. My heart twisted. I'd forgotten about Chiron. How could I do that?

"Mrs. O'Leary," I said. "Please, Chiron's under there. If anyone can dig him out, you can. Find him! Help him!"

I'm not sure how much she understood, but she bounded to the pile and started to dig. Annabeth, Thalia, Grover, and I raced for the elevators.

The bridge to Olympus was dissolving. We stepped out of the elevator onto the white marble walkway, and immediately cracks appeared at our feet.

"Jump!" Grover said, which was easy for him since he's part mountain goat.

He sprang to the next slab of stone while ours tilted sickeningly.

"Gods, I hate heights!" Thalia yelled as she and I leaped. But Annabeth was in no shape for jumping. She stumbled and yelled, "Percy!"

I caught her hand as the pavement fell, crumbling into dust. For a second I thought she was going to pull us both over. Her feet dangled in the open air. Her hand started to slip until I was holding her only by her fingers. Then Grover and Thalia grabbed my legs, and I found extra strength. Annabeth was not going to fall.

I pulled her up and we lay trembling on the pavement. I didn't realize we had our arms around each other until she suddenly tensed.

"Um, thanks," she muttered.

I tried to say Don't mention it, but it came out as, "Uh duh."

"Keep moving!" Grover tugged my shoulder. We untangled ourselves and sprinted across the sky bridge as more stones disintegrated and fell into oblivion. We made it to the edge of the mountain just as the final section collapsed.

Annabeth looked back at the elevator, which was now completely out of reach—a polished set of metal doors hanging in space, attached to nothing, six hundred stories above Manhattan.

"We're marooned," she said. "On our own."

"Blah-ha-ha!" Grover said. "The connection between Olympus and America is dissolving. If it fails—"

"The gods won't move on to another country this time," Thalia said. "This will be the end of Olympus. The final end."

We ran through streets. Mansions were burning. Statues had been hacked down. Trees in the parks were blasted to splinters. It looked like someone had attacked the city with a giant Weedwacker.