"So now you're worried about Luke again," I grumbled.

She stared at me like I'd just dropped from space. "What?"

"Forget it," I muttered. I wondered what Hermes had meant about Annabeth not saving Luke when she'd had the chance. Clearly, she wasn't telling me something. But at the moment I wasn't in the mood to ask. The last thing I wanted to hear about was more of her history with Luke.

"The point is he didn't die in the Styx," I said. "Neither did I. Now I have to face him. We have to defend Olympus."

Annabeth was still studying my face, like she was trying to see differences since my swim in the Styx. "I guess you're right. My mom mentioned—"

"Plan twenty-three."

She rummaged in her pack and pulled out Daedalus's laptop. The blue Delta symbol glowed on the top when she booted it up. She opened a few files and started to read.

"Here it is," she said. "Gods, we have a lot of work to do."

"One of Daedalus's inventions?"

"A lot of inventions . . . dangerous ones. If my mother wants me to use this plan, she must think things are very bad." She looked at me. "What about her message to you: 'Remember the rivers'? What does that mean?"

I shook my head. As usual, I had no clue what the gods were telling me. Which rivers was I supposed to remember? The Styx? The Mississippi?

Just then the Stoll brothers ran in to the throne room.

"You need to see this," Connor said. "Now."

The blue lights in the sky had stopped, so at first I didn't understand what the problem was.

The other campers had gathered in a small park at the edge of the mountain. They were clustered at the guardrail, looking down at Manhattan. The railing was lined with those tourist binoculars, where you could deposit one golden drachma and see the city. Campers were using every single one.

I looked down at the city. I could see almost everything from here—the East River and the Hudson River carving the shape of Manhattan, the grid of streets, the lights of skyscrapers, the dark stretch of Central Park in the north. Everything looked normal, but something was wrong. I felt it in my bones before I realized what it was.

"I don't . . . hear anything," Annabeth said.

That was the problem.

Even from this height, I should've heard the noise of the city—millions of people bustling around, thousands of cars and machines—the hum of a huge metropolis. You don't think about it when you live in New York, but it's always there. Even in the dead of night, New York is never silent.

But it was now.

I felt like my best friend had suddenly dropped dead.

"What did they do?" My voice sounded tight and angry. "What did they do to my city?"

I pushed Michael Yew away from the binoculars and took a look.

In the streets below, traffic had stopped. Pedestrians were lying on the sidewalks, or curled up in doorways. There was no sign of violence, no wrecks, nothing like that. It was as if all the people in New York had simply decided to stop whatever they were doing and pass out.

"Are they dead?" Silena asked in astonishment.

Ice coated my stomach. A line from the prophecy rang in my ears: And see the world in endless sleep. I remembered Grover's story about meeting the god Morpheus in Central Park. You're lucky I'm saving my energy for the main event.

"Not dead," I said. "Morpheus has put the entire island of Manhattan to sleep. The invasion has started."

TEN

I BUY SOME NEW

FRIENDS

Mrs. O'Leary was the only one happy about the sleeping city.

We found her pigging out at an overturned hot dog stand while the owner was curled up on the sidewalk, sucking his thumb.

Argus was waiting for us with his hundred eyes wide open. He didn't say anything. He never does. I guess that's because he supposedly has an eyeball on his tongue. But his face made it clear he was freaking out.

I told him what we'd learned in Olympus, and how the gods would not be riding to the rescue. Argus rolled his eyes in disgust, which looked pretty psychedelic since it made his whole body swirl.

"You'd better get back to camp," I told him. "Guard it as best you can."

He pointed at me and raised his eyebrow quizzically.

"I'm staying," I said.

Argus nodded, like this answer satisfied him. He looked at Annabeth and drew a circle in the air with his finger.

"Yes," Annabeth agreed. "I think it's time."

"For what?" I asked.

Argus rummaged around in the back of his van. He brought out a bronze shield and passed it to Annabeth. It looked pretty much standard issue—the same kind of round shield we always used in capture the flag. But when Annabeth set it on the ground, the reflection on the polished metal changed from sky and buildings to the Statue of Liberty—which wasn't anywhere close to us.

"Whoa," I said. "A video shield."

"One of Daedalus's ideas," Annabeth said. "I had Beckendorf make this before—" She glanced at Silena. "Um, anyway, the shield bends sunlight or moonlight from anywhere in the world to create a reflection. You can literally see any target under the sun or moon, as long as natural light is touching it. Look."

We crowded around as Annabeth concentrated. The image zoomed and spun at first, so I got motion sickness just watching it. We were in the Central Park Zoo, then zooming down East 60th, past Bloomingdale's, then turning on Third Avenue.

"Whoa," Connor Stoll said. "Back up. Zoom in right there."

"What?" Annabeth said nervously. "You see invaders?"

"No, right there—Dylan's Candy Bar." Connor grinned at his brother. "Dude, it's open. And everyone is asleep. Are you thinking what I'm thinking?"

"Connor!" Katie Gardner scolded. She sounded like her mother, Demeter. "This is serious. You are not going to loot a candy store in the middle of a war!"

"Sorry," Connor muttered, but he didn't sound very ashamed.

Annabeth passed her hand in front of the shield, and another scene popped up: FDR Drive, looking across the river at Lighthouse Park.

"This will let us see what's going on across the city," she said. "Thank you, Argus. Hopefully we'll see you back at camp . . . someday."

Argus grunted. He gave me a look that clearly meant Good luck; you'll need it, then climbed into his van. He and the two harpy drivers swerved away, weaving around clusters of idle cars that littered the road.

I whistled for Mrs. O'Leary, and she came bounding over.

"Hey, girl," I said. "You remember Grover? The satyr we met in the park?"

"WOOF!"

I hoped that meant Sure I do! And not, Do you have more hot dogs?

"I need you to find him," I said. "Make sure he's still awake. We're going to need his help. You got that? Find Grover!"

Mrs. O'Leary gave me a sloppy wet kiss, which seemed kind of unnecessary. Then she raced off north.

Pollux crouched next to a sleeping policeman. "I don't get it. Why didn't we fall asleep too? Why just the mortals?"

"This is a huge spell," Silena Beauregard said. "The bigger the spell, the easier it is to resist. If you want to sleep millions of mortals, you've got to cast a very thin layer of magic. Sleeping demigods is much harder."

I stared at her. "When did you learn so much about magic?"

Silena blushed. "I don't spend all my time on my wardrobe."

"Percy," Annabeth called. She was still looking at the shield. "You'd better see this."

The bronze image showed Long Island Sound near La Guardia. A fleet of a dozen speedboats raced through the dark water toward Manhattan. Each boat was packed with demigods in full Greek armor. At the back of the lead boat, a purple banner emblazoned with a black scythe flapped in the night wind. I'd never seen that design before, but it wasn't hard to figure out: the battle flag of Kronos.

"Scan the perimeter of the island," I said. "Quick."

Annabeth shifted the scene south to the harbor. A Staten Island Ferry was plowing through the waves near Ellis Island. The deck was crowded with dracaenae and a whole pack of hellhounds. Swimming in front of the ship was a pod of marine mammals. At first I thought they were dolphins. Then I saw their doglike faces and the swords strapped to their waists, and I realized they were telkhines—sea demons.

The scene shifted again: the Jersey shore, right at the entrance to the Lincoln Tunnel. A hundred assorted monsters were marching past the lanes of stopped traffic: giants with clubs, rogue Cyclopes, a few fire-spitting dragons, and just to rub it in, a World War II-era Sherman tank, pushing cars out of its way as it rumbled into the tunnel.

"What's happening with the mortals outside Manhattan?" I said. "Is the whole state asleep?"

Annabeth frowned. "I don't think so, but it's strange. As far as I can tell from these pictures, Manhattan is totally asleep. Then there's like a fifty-mile radius around the island where time is running really, really slow. The closer you get to Manhattan, the slower it is."

She showed me another scene—a New Jersey highway. It was Saturday evening, so the traffic wasn't as bad as it might've been on a weekday. The drivers looked awake, but the cars were moving at about one mile per hour. Birds flew overhead in slow motion.

"Kronos," I said. "He's slowing time."

"Hecate might be helping," Katie Gardner said. "Look how the cars are all veering away from the Manhattan exits, like they're getting a subconscious message to turn back."

"I don't know." Annabeth sounded really frustrated. She hated not knowing. "But somehow they've surrounded Manhattan in layers of magic. The outside world might not even realize something is wrong. Any mortals coming toward Manhattan will slow down so much they won't know what's happening."

"Like flies in amber," Jake Mason murmured.

Annabeth nodded. "We shouldn't expect any help coming in."

I turned to my friends. They looked stunned and scared, and I couldn't blame them. The shield had shown us at least three hundred enemies on the way. There were forty of us. And we were alone.

"All right," I said. "We're going to hold Manhattan."

Silena tugged at her armor. "Um, Percy, Manhattan is huge."

"We are going to hold it," I said. "We have to."

"He's right," Annabeth said. "The gods of the wind should keep Kronos's forces away from Olympus by air, so he'll try a ground assault. We have to cut off the entrances to the island."

"They have boats," Michael Yew pointed out.

An electric tingle went down my back. Suddenly I understood Athena's advice: Remember the rivers.

"I'll take care of the boats," I said.

Michael frowned. "How?"

"Just leave it to me," I said. "We need to guard the bridges and tunnels. Let's assume they'll try a midtown or downtown assault, at least on their first try. That would be the most direct way to the Empire State Building. Michael, take Apollo's cabin to the Williamsburg Bridge. Katie, Demeter's cabin takes the Brooklyn-Battery Tunnel. Grow thorn bushes and poison ivy in the tunnel. Do whatever you have to do, but keep them out of there! Conner, take half of Hermes cabin and cover the Manhattan Bridge. Travis, you take the other half and cover the Brooklyn Bridge. And no stopping for looting or pillaging!"