I sat in the driver's seat of Grover's Lamborghini. Grover was asleep in the back. He'd finally given up trying to impress Zoe and Bianca with his pipe music after he played "Poison Ivy" and caused that very stuff to sprout from their Lexus's air conditioner.

As I watched the sun go down, I thought of Annabeth. I was afraid to go to sleep. I was worried what I might dream.

"Oh, don't be afraid of dreams," a voice said right next to me.

I looked over. Somehow, I wasn't surprised to find the homeless guy from the rail yard sitting in the shotgun seat. His jeans were so worn out they were almost white. His coat was ripped, with stuffing coming out. He looked kind of like a teddy bear that had been run over by a truck.

"If it weren't for dreams," he said, "I wouldn't know half the things I know about the future. They're better than Olympus tabloids." He cleared his throat, then held up his hands dramatically:

"Dreams like a podcast,

Downloading truth in my ears.

They tell me cool stuff"

Apollo?" I guessed, because I figured nobody else could make a haiku that bad.

He put his finger to his lips. "I'm incognito. Call me Fred."

"A god named Fred?"

"Eh, well… Zeus insists on certain rules. Hands off, when there's a human quest. Even when something really major is wrong. But nobody messes with my baby sister. Nobody."

"Can you help us, then?"

"Shhh. I already have. Haven't you been looking outside?"

"The train. How fast are we moving?"

Apollo chuckled. "Fast enough. Unfortunately, we're running out of time. It's almost sunset. But I imagine we'll get you across a good chunk of America, at least."

"But where is Artemis?"

His face darkened. "I know a lot, and I see a lot. But even I don't know that. She's… clouded from me. I don't like it."

"And Annabeth?"

He frowned. "Oh, you mean that girl you lost? Hmm. I don't know."

I tried not to feel mad. I knew the gods had a hard time taking mortals seriously, even half-bloods. We lived such short lives, compared to the gods.

"What about the monster Artemis was seeking?" I asked. "Do you know what it is?"

"No," Apollo said. "But there is one who might. If you haven't yet found the monster when you reach San Francisco, seek out Nereus, the Old Man of the Sea. He has a long memory and a sharp eye. He has the gift of knowledge sometimes kept obscure from my Oracle."

"But it's your Oracle," I protested. "Can't you tell us what the prophecy means?"

Apollo sighed. "You might as well ask an artist to explain his art, or ask a poet to explain his poem. It defeats the purpose. The meaning is only clear through the search."

"In other words, you don't know."

Apollo checked his watch. "Ah, look at the time! I have to run. I doubt I can risk helping you again, Percy, but remember what I said! Get some sleep! And when you return, I expect a good haiku about your journey!"

I wanted to protest that I wasn't tired and I'd never made up a haiku in my life, but Apollo snapped his fingers, and the next thing I knew I was closing my eyes.

In my dream, I was somebody else. I was wearing an old-fashioned Greek tunic, which was a little too breezy downstairs, and laced leather sandals. The Nemean Lion's skin was wrapped around my back like a cape, and I was running somewhere, being pulled along by a girl who was tightly gripping my hand.

"Hurry!" she said. It was too dark to see her face clearly, but I could hear the fear in her voice. "He will find us!"

It was nighttime. A million stars blazed above. We were running through tall grass, and the scent of a thousand different flowers made the air intoxicating. It was a beautiful garden, and yet the girl was leading me through it, as if we were about to die.

"I'm not afraid," I tried to tell her.

"You should be!" she said, pulling me along. She had long dark hair braided down her back. Her silk robes glowed faintly in the starlight.

We raced up the side of the hill. She pulled me behind a thorn bush and we collapsed, both breathing heavily. I didn't know why the girl was scared. The garden seemed so peaceful. And I felt strong. Stronger than I'd ever felt before.

"There is no need to run," I told her. My voice sounded deeper, much more confident. "I have bested a thousand monsters with my bare hands."

"Not this one," the girl said. "Ladon is too strong. You must go around, up the mountain to my father. It is the only way."

The hurt in her voice surprised me. She was really concerned, almost like she cared about me.

"I don't trust your father," I said.

"You should not," the girl agreed. "You will have to trick him. But you cannot take the prize directly. You will die. "

I chuckled. "Then why don't you help me, pretty one?"

"I… I am afraid. Ladon will stop me. My sisters, if they found out… they would disown me."

"Then there's nothing for it." I stood up, rubbing my hands together.

"Wait. " the girl said.

She seemed to be agonizing over a decision. Then, her fingers trembling, she reached up and plucked a long white brooch from her hair. "If you must fight, take this. My mother, Pleione, gave it to me. She was a daughter of the ocean, and the ocean's power is within it. My immortal power."

The girl breathed on the pin and it glowed faintly. It gleamed in the starlight like polished abalone.

"Take it," she told me. "And make of it a weapon."

I laughed. "A hairpin? How will this slay Ladon, pretty one?"

"It may not," she admitted. "But it is all I can offer, if you insist on being stubborn."

The girl's voice softened my heart. I reached down and took the hairpin, and as I did, it grew longer and heavier in my hand, until I held a familiar bronze sword.

"Well balanced," I said. "Though I usually prefer to use my bare hands. What shall I name this blade?"

"Anaklusmos," the girl said sadly. "The current that takes one by surprise. And before you know it, you have been swept out to sea."

Before I could thank her, there was a trampling sound in the grass, a hiss like air escaping a tire, and the girl said, "Too late! He is here!"

I sat bolt upright in the Lamborghini's drivers seat. Grover was shaking my arm.

"Percy," he said. "It's morning. The train's stopped. Come on!"

I tried to shake off my drowsiness. Thalia, Zoe, and Bianca had already rolled up the metal curtains. Outside were snowy mountains dotted with pine trees, the sun rising red between two peaks.

I fished my pen out of my pocket and stared at it. Anaklusmos, the Ancient Greek name for Riptide. A different form, but I was sure it was the same blade I'd seen in my dream.

And I was sure of something else, too. The girl I had seen was Zoe Nightshade.