Grover was having a snack in the living room. He was dressed for battle in an armored shirt made from tree bark and twist ties, with his wooden cudgel and his reed pipes hanging from his belt.

The Demeter cabin had whipped up a whole buffet in the hotel kitchens—everything from pizza to pineapple ice cream. Unfortunately, Grover was eating the furniture. He'd already chewed the stuffing off a fancy chair and was now gnawing the armrest.

"Dude," I said, "we're only borrowing this place."

"Blah-ha-ha!" He had stuffing all over his face. "Sorry, Percy. It's just . . . Louis the Sixteenth furniture. Delicious. Plus I always eat furniture when I get—"

"When you get nervous," I said. "Yeah, I know. So what's up?"

He clopped on his hooves. "I heard about Annabeth. Is she . . .?"

"She's going to be fine. She's resting."

Grover took a deep breath. "That's good. I've mobilized most of the nature spirits in the city—well, the ones that will listen to me, anyway." He rubbed his forehead. "I had no idea acorns could hurt so much. Anyway, we're helping out as much as we can."

He told me about the skirmishes they'd seen. Mostly they'd been covering uptown, where we didn't have enough demigods. Hellhounds had appeared in all sorts of places, shadow-traveling inside our lines, and the dryads and satyrs had been fighting them off. A young dragon had appeared in Harlem, and a dozen wood nymphs died before the monster was finally defeated.

As Grover talked, Thalia entered the room with two of her lieutenants. She nodded to me grimly, went outside to check on Annabeth, and came back in. She listened while Grover completed his report—the details getting worse and worse.

"We lost twenty satyrs against some giants at Fort Washington," he said, his voice trembling. "Almost half my kinsmen. River spirits drowned the giants in the end, but . . ."

Thalia shouldered her bow. "Percy, Kronos's forces are still gathering at every bridge and tunnel. And Kronos isn't the only Titan. One of my Hunters spotted a huge man in golden armor mustering an army on the Jersey shore. I'm not sure who he is, but he radiates power like only a Titan or god."

I remembered the golden Titan from my dream—the one on Mount Othrys who erupted into flames.

"Great," I said. "Any good news?"

Thalia shrugged. "We've sealed off the subway tunnels into Manhattan. My best trappers took care of it. Also, it seems like the enemy is waiting for tonight to attack. I think Luke"—she caught herself—"I mean Kronos needs time to regenerate after each fight. He's still not comfortable with his new form. It's taking a lot of his power to slow time around the city."

Grover nodded. "Most of his forces are more powerful at night, too. But they'll be back after sundown."

I tried to think clearly. "Okay. Any word from the gods?"

Thalia shook her head. "I know Lady Artemis would be here if she could. Athena, too. But Zeus has ordered them to stay at his side. The last I heard, Typhon was destroying the Ohio River valley. He should reach the Appalachian Mountains by midday."

"So at best," I said, "we've got another two days before he arrives."

Jake Mason cleared his throat. He'd been standing there so silently I'd almost forgotten he was in the room.

"Percy, something else," he said. "The way Kronos showed up at the Williamsburg Bridge, like he knew you were going there. And he shifted his forces to our weakest points. As soon as we deployed, he changed tactics. He barely touched the Lincoln Tunnel, where the Hunters were strong. He went for our weakest spots, like he knew."

"Like he had inside information," I said. "The spy."

"What spy?" Thalia demanded.

I told her about the silver charm Kronos had shown me, the communication device.

"That's bad," she said. "Very bad."

"It could be anyone," Jake said. "We were all standing there when Percy gave the orders."

"But what can we do?" Grover asked. "Frisk every demigod until we find a scythe charm?"

They all looked at me, waiting for a decision. I couldn't afford to show how panicked I felt, even if things seemed hopeless.

"We keep fighting," I said. "We can't obsess about this spy. If we're suspicious of each other, we'll just tear ourselves apart. You guys were awesome last night. I couldn't ask for a braver army. Let's set up a rotation for the watches. Rest up while you can. We've got a long night ahead of us."

The demigods mumbled agreement. They went their separate ways to sleep or eat or repair their weapons.

"Percy, you too," Thalia said. "We'll keep an eye on things. Go lie down. We need you in good shape for tonight."

I didn't argue too hard. I found the nearest bedroom and crashed on the canopied bed. I thought I was too wired to sleep, but my eyes closed almost immediately.

In my dream, I saw Nico di Angelo alone in the gardens of Hades. He'd just dug a hole in one of Persephone's flower beds, which I didn't figure would make the queen very happy.

He poured a goblet of wine into the hole and began to chant. "Let the dead taste again. Let them rise and take this offering. Maria di Angelo, show yourself!"

White smoke gathered. A human figure formed, but it wasn't Nico's mother. It was a girl with dark hair, olive skin, and the silvery clothes of a Hunter.

"Bianca," Nico said. "But—"

Don't summon our mother, Nico, she warned. She is the one spirit you are forbidden to see.

"Why?" he demanded. "What's our father hiding?"

Pain, Bianca said. Hatred. A curse that stretches back to the Great Prophecy.

"What do you mean?" Nico said. "I have to know!"

The knowledge will only hurt you. Remember what I said: holding grudges is a fatal flaw for children of Hades.

"I know that," Nico said. "But I'm not the same as I used to be, Bianca. Stop trying to protect me!"

Brother, you don't understand—

Nico swiped his hand through the mist, and Bianca s image dissipated.

"Maria di Angelo," he said again. "Speak to me!"

A different image formed. It was a scene rather than a single ghost. In the mist, I saw Nico and Bianca as little children, playing in the lobby of an elegant hotel, chasing each other around marble columns.

A woman sat on a nearby sofa. She wore a black dress, gloves, and a black veiled hat like a star from an old 1940s movie. She had Bianca's smile and Nico's eyes.

On a chair next to her sat a large oily man in a black pinstripe suit. With a shock, I realized it was Hades. He was leaning toward the woman, using his hands as he talked, like he was agitated.

"Please, my dear," he said. "You must come to the Underworld. I don't care what Persephone thinks! I can keep you safe there."

"No, my love." She spoke with an Italian accent. "Raise our children in the land of the dead? I will not do this."

"Maria, listen to me. The war in Europe has turned the other gods against me. A prophecy has been made. My children are no longer safe. Poseidon and Zeus have forced me into an agreement. None of us are to have demigod children ever again."

"But you already have Nico and Bianca. Surely—"

"No! The prophecy warns of a child who turns sixteen. Zeus has decreed that the children I currently have must be turned over to Camp Half-Blood for proper training, but I know what he means. At best they'll be watched, imprisoned, turned against their father. Even more likely, he will not take a chance. He won't allow my demigod children to reach sixteen. He'll find a way to destroy them, and I won't risk that!"

"Certamente," Maria said. "We will stay together. Zeus is un imbecile."

I couldn't help admiring her courage, but Hades glanced nervously at the ceiling. "Maria, please. I told you, Zeus gave me a deadline of last week to turn over the children. His wrath will be horrible, and I cannot hide you forever. As long as you are with the children, you are in danger too."

Maria smiled, and again it was creepy how much she looked like her daughter. "You are a god, my love. You will protect us. But I will not take Nico and Bianca to the Underworld."

Hades wrung his hands. "Then, there is another option. I know a place in the desert where time stands still. I could send the children there, just for a while, for their own safety, and we could be together. I will build you a golden palace by the Styx."

Maria di Angelo laughed gently. "You are a kind man, my love. A generous man. The other gods should see you as I do, and they would not fear you so. But Nico and Bianca need their mother. Besides, they are only children. The gods wouldn't really hurt them."

"You don't know my family," Hades said darkly. "Please, Maria, I can't lose you."

She touched his lips with her fingers. "You will not lose me. Wait for me while I get my purse. Watch the children."

She kissed the lord of the dead and rose from the sofa. Hades watched her walk upstairs as if her every step away caused him pain.

A moment later, he tensed. The children stopped playing as if they sensed something too.

"No!" Hades said. But even his godly powers were too slow. He only had time to erect a wall of black energy around the children before the hotel exploded.

The force was so violent, the entire mist image dissolved.

When it came into focus again, I saw Hades kneeling in the ruins, holding the broken form of Maria di Angelo. Fires still burned all around him. Lightning flashed across the sky, and thunder rumbled.

Little Nico and Bianca stared at their mother uncomprehendingly. The Fury Alecto appeared behind them, hissing and flapping her leathery wings. The children didn't seem to notice her.

"Zeus!" Hades shook his fist at the sky. "I will crush you for this! I will bring her back!"

"My lord, you cannot," Alecto warned. "You of all immortals must respect the laws of death."

Hades glowed with rage. I thought he would show his true form and vaporize his own children, but at the last moment he seemed to regain control.

"Take them," he told Alecto, choking back a sob. "Wash their memories clean in the Lethe and bring them to the Lotus Hotel. Zeus will not harm them there."

"As you wish, my lord," Alecto said. "And the woman's body?

"Take her as well," he said bitterly. "Give her the ancient rites."

Alecto, the children, and Maria's body dissolved into shadows, leaving Hades alone in the ruins.

"I warned you," a new voice said.

Hades turned. A girl in a multicolored dress stood by the smoldering remains of the sofa. She had short black hair and sad eyes. She was no more than twelve. I didn't know her, but she looked strangely familiar.

"You dare come here?" Hades growled. "I should blast you to dust!"

"You cannot," the girl said. "The power of Delphi protects me."

With a chill, I realized I was looking at the Oracle of Delphi, back when she was alive and young. Somehow, seeing her like this was even spookier than seeing her as a mummy.

"You've killed the woman I loved!" Hades roared. "Your prophecy brought us to this.'"