“And you, Percy,” Hermes said, “have a shorter deadline than you realize to complete your quest. Your friends should be coming right about … now.”

I heard Annabeth’s voice calling my name from the sand dunes. Tyson, too, was shouting from a little bit farther away.

“I hope I packed well for you,” Hermes said. “I do have some experience with travel.”

He snapped his fingers and three yellow duffel bags appeared at my feet. “Waterproof, of course. If you ask nicely, your father should be able to help you reach the ship.”

“Ship?”

Hermes pointed. Sure enough, a big cruise ship was cutting across Long Island Sound, its white-and-gold lights glowing against the dark water.

“Wait,” I said. “I don’t understand any of this. I haven’t even agreed to go!”

“I’d make up your mind in the next five minutes, if I were you,” Hermes advised. “That’s when the harpies will come to eat you. Now, good night, cousin, and dare I say it? May the gods go with you.”

He opened his hand and the caduceus flew into it.

Good luck, Martha told me.

Bring me back a rat, George said.

The caduceus changed into a cell phone and Hermes slipped it into his pocket.

He jogged off down the beach. Twenty paces away, he shimmered and vanished, leaving me alone with a thermos, a bottle of chewable vitamins, and five minutes to make an impossible decision.

Chapter Eight: We Board The Princess Andromeda

I was staring at the waves when Annabeth and Tyson found me.

“What’s going on?” Annabeth asked. “I heard you calling for help!”

“Me, too!” Tyson said. “Heard you yell, ‘Bad things are attacking!’”

“I didn’t call you guys,” I said. “I’m fine.”

“But then who …” Annabeth noticed the three yellow duffel bags, then the thermos and the bottle of vitamins I was holding. “What—”

“Just listen,” I said. “We don’t have much time.”

I told them about my conversation with Hermes. By the time I was finished, I could hear screeching in the distance—patrol harpies picking up our scent.

“Percy,” Annabeth said, “we have to do the quest.”

“We’ll get expelled, you know. Trust me, I’m an expert at getting expelled.”

“So? If we fail, there won’t be any camp to come back to.”

“Yeah, but you promised Chiron—”

“I promised I’d keep you from danger. I can only do that by coming with you! Tyson can stay behind and tell them—”

“I want to go,” Tyson said.

“No!” Annabeth’s voice sounded close to panic. “I mean … Percy, come on. You know that’s impossible.”

I wondered again why she had such a grudge against Cyclopes. There was something she wasn’t telling me.

She and Tyson both looked at me, waiting for an answer. Meanwhile, the cruise ship was getting farther and farther away.

The thing was, part of me didn’t want Tyson along. I’d spent the last three days in close quarters with the guy, getting razzed by the other campers and embarrassed a million times a day, constantly reminded that I was related to him. I needed some space.

Plus, I didn’t know how much help he’d be, or how I’d keep him safe. Sure, he was strong, but Tyson was a little kid in Cyclops terms, maybe seven or eight years old, mentally. I could see him freaking out and starting to cry while we were trying to sneak past a monster or something. He’d get us all killed.

On the other hand, the sound of the harpies was getting closer….

“We can’t leave him,” I decided. “Tantalus will punish him for us being gone.”

“Percy,” Annabeth said, trying to keep her cool, “we’re going to Polyphemus’s island!

Polyphemus is an S-i-k … a C-y-k…” She stamped her foot in frustration. As smart as she was, Annabeth was dyslexic, too. We could’ve been there all night while she tried to spell Cyclops. “You know what I mean!”

“Tyson can go,” I insisted, “if he wants to.”

Tyson clapped his hands. “Want to!”

Annabeth gave me the evil eye, but I guess she could tell I wasn’t going to change my mind.

Or maybe she just knew we didn’t have time to argue.

“All right,” she said. “How do we get to that ship?”

“Hermes said my father would help.”

“Well then, Seaweed Brain? What are you waiting for?”

I’d always had a hard time calling on my father, or praying, or whatever you want to call it, but I stepped into the waves.

“Urn, Dad?” I called. “How’s it going?”

“Percy!” Annabeth whispered. “We’re in a hurry!”

“We need your help,” I called a little louder. “We need to get to that ship, like, before we get eaten and stuff, so …”

At first, nothing happened. Waves crashed against the shore like normal. The harpies sounded like they were right behind the sand dunes. Then, about a hundred yards out to sea, three white lines appeared on the surface. They moved fast toward the shore, like claws ripping through the ocean.

As they neared the beach, the surf burst apart and the heads of three white stallions reared out of the waves.

Tyson caught his breath. “Fish ponies!”

He was right. As the creatures pulled themselves onto the sand, I saw that they were only horses in the front; their back halves were silvery fish bodies, with glistening scales and rainbow tail fins.

“Hippocampi!” Annabeth said. “They’re beautiful.”

The nearest one whinnied in appreciation and nuzzled Annabeth.

“We’ll admire them later,” I said. “Come on!”

“There!” a voice screeched behind us. “Bad children out of cabins! Snack time for lucky harpies!”

Five of them were fluttering over the top of the dunes—plump little hags with pinched faces and talons and feathery wings too small for their bodies. They reminded me of miniature cafeteria ladies who’d been crossbred with dodo birds. They weren’t very fast, thank the gods, but they were vicious if they caught you.

“Tyson!” I said. “Grab a duffel bag!”

He was still staring at the hippocampi with his mouth hanging open, “Tyson!”

“Uh?”

“Come on!”

With Annabeth’s help I got him moving. We gathered the bags and mounted our steeds.

Poseidon must’ve known Tyson was one of the passengers, because one hippocampus was much larger than the other two—just right for carrying a Cyclops.

“Giddyup!” I said. My hippocampus turned and plunged into the waves. Annabeth’s and Tyson’s followed right behind.

The harpies cursed at us, wailing for their snacks to come back, but the hippocampi raced over the water at the speed of Jet Skis. The harpies fell behind, and soon the shore of Camp Half-Blood was nothing but a dark smudge. I wondered if I’d ever see the place again. But right then I had other problems.

The cruise ship was now looming in front of us—our ride toward Florida and the Sea of Monsters.

Riding the hippocampus was even easier than riding a pegasus. We zipped along with the wind in our faces, speeding through the waves so smooth and steady I hardly needed to hold on at all.

As we got closer to the cruise ship, I realized just how huge it was. I felt as though I were looking up at a building in Manhattan. The white hull was at least ten stories tall, topped with another dozen levels of decks with brightly lit balconies and portholes. The ship’s name was painted just above the bow line in black letters, lit with a spotlight. It took me a few seconds to decipher it:

PRINCESS ANDROMEDA 

Attached to the bow was a huge masthead—a three-story-tall woman wearing a white Greek chiton, sculpted to look as if she were chained to the front of the ship. She was young and beautiful, with flowing black hair, but her expression was one of absolute terror. Why anybody would want a screaming princess on the front of their vacation ship, I had no idea.

I remembered the myth about Andromeda and how she had been chained to a rock by her own parents as a sacrifice to a sea monster. Maybe she’d gotten too many F’s on her report card or something. Anyway, my namesake, Perseus, had saved her just in time and turned the sea monster to stone using the head of Medusa.

That Perseus always won. That’s why my mom had named me after him, even though he was a son of Zeus and I was a son of Poseidon. The original Perseus was one of the only heroes in the Greek myths who got a happy ending. The others died—betrayed, mauled, mutilated, poisoned, or cursed by the gods. My mom hoped I would inherit Perseus’s luck. Judging by how my life was going so far, I wasn’t real optimistic.

“How do we get aboard?” Annabeth shouted over the noise of the waves, but the hippocampi seemed to know what we needed. They skimmed along the starboard side of the ship, riding easily through its huge wake, and pulled up next to a service ladder riveted to the side of the hull.

“You first,” I told Annabeth.

She slung her duffel bag over her shoulder and grabbed the bottom rung. Once she’d hoisted herself onto the ladder, her hippocampus whinnied a farewell and dove underwater.

Annabeth began to climb. I let her get a few rungs up, then followed her.

Finally it was just Tyson in the water. His hippocampus was treating him to 360° aerials and backward ollies, and Tyson was laughing so hysterically, the sound echoed up the side of the ship.

“Tyson, shhh!” I said. “Come on, big guy!”

“Can’t we take Rainbow?” he asked, his smile fading.

I stared at him. “Rainbow?”

The hippocampus whinnied as if he liked his new name.

“Um, we have to go,” I said. “Rainbow … well, he can’t climb ladders.”

Tyson sniffled. He buried his face in the hippocampus’s mane. “I will miss you, Rainbow!”

The hippocampus made a neighing sound I could’ve sworn was crying.

“Maybe we’ll see him again sometime,” I suggested.

“Oh, please!” Tyson said, perking up immediately. “Tomorrow!”

I didn’t make any promises, but I finally convinced Tyson to say his farewells and grab hold of the ladder. With a final sad whinny, Rainbow the hippocampus did a back-flip and dove into the sea.

The ladder led to a maintenance deck stacked with yellow lifeboats. There was a set of locked double doors, which Annabeth managed to pry open with her knife and a fair amount of cursing in Ancient Greek.

I figured we’d have to sneak around, being stowaways and all, but after checking a few corridors and peering over a balcony into a huge central promenade lined with closed shops, I began to realize there was nobody to hide from. I mean, sure it was the middle of the night, but we walked half the length of the boat and met no one. We passed forty or fifty cabin doors and heard no sound behind any of them.

“It’s a ghost ship,” I murmured.