I told him what was happening. Then I told him my plan.

His voice was silent for a long time.

Percy, what you ask is impossible. My palace—

"Dad, Kronos sent an army against you on purpose. He wants to divide you from the other gods because he knows you could tip the scales."

Be that as it may, he attacks my home.

"I'm at your home," I said. "Olympus."

The floor shook. A wave of anger washed over my mind. I thought I'd gone too far, but then the trembling eased. In the background of my mental link, I heard underwater explosions and the sound of battle cries: Cyclopes bellowing, mermen shouting.

"Is Tyson okay?" I asked.

The question seemed to take my dad by surprise. He's fine. Doing much better than I expected. Though "peanut butter" is a strange battle cry.

"You let him fight?"

Stop changing the subject! You realize what you are asking me to do? My palace will be destroyed.

"And Olympus might be saved."

Do you have any idea how long I've worked on remodeling this palace? The game room alone took six hundred years.

"Dad—"

Very well! It shall be as you say. But my son, pray this works.

"I am praying. I'm talking to you, right?"

Oh . . . yes. Good point. Amphitrite—incoming!

The sound of a large explosion shattered our connection.

I slipped down from the throne.

Grover studied me nervously. "Are you okay? You turned pale and . . . you started smoking."

"I did not!" Then I looked at my arms. Steam was curling off my shirtsleeves. The hair on my arms was singed.

"If you'd sat there any longer," Annabeth said, "you would've spontaneously combusted. I hope the conversation was worth it?"

Moo, said the Ophiotaurus in his sphere of water.

"We'll find out soon," I said.

Just then the doors of the throne room swung open. Thalia marched in. Her bow was snapped in half and her quiver was empty.

"You've got to get down there," she told us. "The enemy is advancing. And Kronos is leading them."

EIGHTEEN

MY PARENTS GO

COMMANDO

By the time we got to the street, it was too late.

Campers and Hunters lay wounded on the ground. Clarisse must've lost a fight with a Hyperborean giant, because she and her chariot were frozen in a block of ice. The centaurs were nowhere to be seen. Either they'd panicked and ran or they'd been disintegrated.

The Titan army ringed the building, standing maybe twenty feet from the doors. Kronos's vanguard was in the lead: Ethan Nakamura, the dracaena queen in her green armor, and two Hyperboreans. I didn't see Prometheus. The slimy weasel was probably hiding back at their headquarters. But Kronos himself stood right in front with his scythe in hand.

The only thing standing in his way was . . .

"Chiron," Annabeth said, her voice trembling.

If Chiron heard us, he didn't answer. He had an arrow notched, aimed straight at Kronos's face.

As soon as Kronos saw me, his gold eyes flared. Every muscle in my body froze. Then the Titan lord turned his attention back to Chiron. "Step aside, little son."

Hearing Luke call Chiron his son was weird enough, but Kronos put contempt in his voice, like son was the worst word he could think of.

"I'm afraid not." Chiron's tone was steely calm, the way he gets when he's really angry.

I tried to move, but my feet felt like concrete. Annabeth, Grover, and Thalia were straining too, like they were just as stuck.

"Chiron!" Annabeth said. "Look out!"

The dracaena queen became impatient and charged. Chiron's arrow flew straight between her eyes and she vaporized on the spot, her empty armor clattering to the asphalt.

Chiron reached for another arrow, but his quiver was empty. He dropped the bow and drew his sword. I knew he hated fighting with a sword. It was never his favorite weapon.

Kronos chuckled. He advanced a step, and Chiron's horse-half skittered nervously. His tail flicked back and forth.

"You're a teacher," Kronos sneered. "Not a hero."

"Luke was a hero," Chiron said. "He was a good one, until you corrupted him."

"FOOL!" Kronos's voice shook the city. "You filled his head with empty promises. You said the gods cared about me!"

"Me," Chiron noticed. "You said me."

Kronos looked confused, and in that moment, Chiron struck. It was a good maneuver—a feint followed by a strike to the face. I couldn't have done better myself, but Kronos was quick. He had all of Luke's fighting skill, which was a lot. He knocked aside Chiron's blade and yelled, "BACK!"

A blinding white light exploded between the Titan and the centaur. Chiron flew into the side of the building with such force the wall crumbled and collapsed on top of him.

"No!" Annabeth wailed. The freezing spell broke. We ran toward our teacher, but there was no sign of him. Thalia and I pulled helplessly at the bricks while a ripple of ugly laughter ran through the Titan's army.

"YOU!" Annabeth turned on Luke. "To think that I . . . that I thought—"

She drew her knife.

"Annabeth, don't." I tried to take her arm, but she shook me off.

She attacked Kronos, and his smug smile faded. Perhaps some part of Luke remembered that he used to like this girl, used to take care of her when she was little. She plunged her knife between the straps of his armor, right at his collar bone. The blade should've sunk into his chest. Instead it bounced off. Annabeth doubled over, clutching her arm to her stomach. The jolt might've been enough to dislocate her bad shoulder.

I yanked her back as Kronos swung his scythe, slicing the air where she'd been standing.

She fought me and screamed, "I HATE you!" I wasn't sure who she was talking to—me or Luke or Kronos. Tears streaked the dust on her face.

"I have to fight him," I told her.

"It's my fight too, Percy!"

Kronos laughed. "So much spirit. I can see why Luke wanted to spare you. Unfortunately, that won't be possible."

He raised his scythe. I got ready to defend, but before Kronos could strike, a dog's howl pierced the air somewhere behind the Titan's army. "Arroooooooo!"

It was too much to hope, but I called, "Mrs. O'Leary?"

The enemy forces stirred uneasily. Then the strangest thing happened. They began to part, clearing a path through the street like something behind them was forcing them to.

Soon there was a free aisle down the center of Fifth Avenue. Standing at the end of the block was my giant dog, and a small figure in black armor.

"Nico?" I called.

"ROWWF!" Mrs. O'Leary bounded toward me, ignoring the growling monsters on either side. Nico strode forward. The enemy army fell back before him like he radiated death, which of course he did.

Through the face guard of his skull-shaped helmet, he smiled. "Got your message. Is it too late to join the party?"

"Son of Hades." Kronos spit on the ground. "Do you love death so much you wish to experience it?"

"Your death," Nico said, "would be great for me."

"I'm immortal, you fool! I have escaped Tartarus. You have no business here, and no chance to live."

Nico drew his sword—three feet of wicked sharp Stygian iron, black as a nightmare. "I don't agree."

The ground rumbled. Cracks appeared in the road, the sidewalks, the sides of the buildings. Skeletal hands grasped the air as the dead clawed their way into the world of the living. There were thousands of them, and as they emerged, the Titan's monsters got jumpy and started to back up.

"HOLD YOUR GROUND!" Kronos demanded. "The dead are no match for us."

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.