My mind was reeling. How could I not go to camp? I wanted to ask a million questions, but just then the kitchen clock chimed the half-hour.

My mom looked almost relieved. "Seven-thirty, dear. You should go. Tyson will be waiting."

"But—"

"Percy, we'll talk this afternoon. Go on to school."

That was the last thing I wanted to do, but my mom had this fragile look in her eyes—a kind of warning, like if I pushed her too hard she'd start to cry. Besides, she was right about my friend Tyson. I had to meet him at the subway station on time or he'd get upset. He was scared of traveling underground alone.

I gathered up my stuff, but I stopped in the doorway. "Mom, this problem at camp. Does it… could it have anything to do with my dream about Grover?"

She wouldn't meet my eyes. "We'll talk this afternoon, dear. I'll explain… as much as I can."

Reluctantly, I told her good-bye. I jogged downstairs to catch the Number Two train.

I didn't know it at the time, but my mom and I would never get to have our afternoon talk.

In fact, I wouldn't be seeing home for a long, long time.

As I stepped outside, I glanced at the brownstone building across the street. Just for a second I saw a dark shape in the morning sunlight—a human silhouette against the brick wall, a shadow that belonged to no one.

Then it rippled and vanished.

My day started normal. Or as normal as it ever gets at Meriwether College Prep.

See, it's this «progressive» school in downtown Manhattan, which means we sit on beanbag chairs instead of at desks, and we don't get grades, and the teachers wear jeans and rock concert T-shirts to work.

That's all cool with me. I mean, I'm ADHD and dyslexic, like most half-bloods, so I'd never done that great in regular schools even before they kicked me out. The only bad thing about Meriwether was that the teachers always looked on the bright side of things, and the kids weren't always… well, bright.

Take my first class today: English. The whole middle school had read this book called Lord of the Flies, where all these kids get marooned on an island and go psycho. So for our final exam, our teachers sent us into the break yard to spend an hour with no adult supervision to see what would happen. What happened was a massive wedgie contest between the seventh and eighth graders, two pebble fights, and a full-tackle basketball game. The school bully, Matt Sloan, led most of those activities.

Sloan wasn't big or strong, but he acted like he was. He had eyes like a pit bull, and shaggy black hair, and he always dressed in expensive but sloppy clothes, like he wanted everybody to see how little he cared about his family's money. One of his front teeth was chipped from the time he'd taken his daddy's Porsche for a joyride and run into a PLEASE SLOW DOWN FOR CHILDREN sign.

Anyway, Sloan was giving everybody wedgies until he made the mistake of trying it on my friend Tyson.

Tyson was the only homeless kid at Meriwether College Prep. As near as my mom and I could figure, he'd been abandoned by his parents when he was very young, probably because he was so… different. He was six-foot-three and built like the Abominable Snowman, but he cried a lot and was scared of just about everything, including his own reflection. His face was kind of misshapen and brutal-looking. I couldn't tell you what color his eyes were, because I could never make myself look higher than his crooked teeth. His voice was deep, but he talked funny, like a much younger kid—I guess because he'd never gone to school before coming to Meriwether. He wore tattered jeans, grimy size-twenty sneakers, and a plaid flannel shirt with holes in it. He smelled like a New York City alleyway, because that's where he lived, in a cardboard refrigerator box off 72nd Street.

Meriwether Prep had adopted him as a community service project so all the students could feel good about themselves. Unfortunately, most of them couldn't stand Tyson. Once they discovered he was a big softie, despite his massive strength and his scary looks, they made themselves feel good by picking on him. I was pretty much his only friend, which meant he was my only friend.

My mom had complained to the school a million times that they weren't doing enough to help him. She'd called social services, but nothing ever seemed to happen. The social workers claimed Tyson didn't exist. They swore up and down that they'd visited the alley we described and couldn't find him, though how you miss a giant kid living in a refrigerator box, I don't know.

Anyway, Matt Sloan snuck up behind him and tried to give him a wedgie, and Tyson panicked. He swatted Sloan away a little too hard. Sloan flew fifteen feet and got tangled in the little kids' tire swing.

"You freak!" Sloan yelled. "Why don't you go back to your cardboard box!"

Tyson started sobbing. He sat down on the jungle gym so hard he bent the bar, and buried his head in his hands.

"Take it back, Sloan!" I shouted.

Sloan just sneered at me. "Why do you even bother, Jackson? You might have friends if you weren't always sticking up for that freak."

I balled my fists. I hoped my face wasn't as red as it felt. "He's not a freak. He's just…"

I tried to think of the right thing to say, but Sloan wasn't listening. He and his big ugly friends were too busy laughing. I wondered if it were my imagination, or if Sloan had more goons hanging around him than usual. I was used to seeing him with two or three, but today he had like, half a dozen more, and I was pretty sure I'd never seen them before.

"Just wait till PE, Jackson," Sloan called. "You are so dead."

When first period ended, our English teacher, Mr. de Milo, came outside to inspect the carnage. He pronounced that we'd understood Lord of the Flies perfectly. We all passed his course, and we should never, never grow up to be violent people. Matt Sloan nodded earnestly, then gave me a chip-toothed grin.

I had to promise to buy Tyson an extra peanut butter sandwich at lunch to get him to stop sobbing.

"I… I am a freak?" he asked me.

"No," I promised, gritting my teeth. "Matt Sloan is the freak."

Tyson sniffled. "You are a good friend. Miss you next year if… if I can't…"

His voice trembled. I realized he didn't know if he'd be invited back next year for the community service project. I wondered if the headmaster had even bothered talking to him about it.

"Don't worry, big guy," I managed. "Everything's going to be fine."

Tyson gave me such a grateful look I felt like a big liar. How could I promise a kid like him that anything would be fine?

Our next exam was science. Mrs. Tesla told us that we had to mix chemicals until we succeeded in making something explode, Tyson was my lab partner. His hands were way too big for the tiny vials we were supposed to use. He accidentally knocked a tray of chemicals off the counter and made an orange mushroom cloud in the trash can.

After Mrs. Tesla evacuated the lab and called the hazardous waste removal squad, she praised Tyson and me for being natural chemists. We were the first ones who'd ever aced her exam in under thirty seconds.

I was glad the morning went fast, because it kept me from thinking too much about my problems. I couldn't stand the idea that something might be wrong at camp. Even worse, I couldn't shake the memory of my bad dream. I had a terrible feeling that Grover was in danger.

In social studies, while we were drawing latitude/longitude maps, I opened my notebook and stared at the photo inside—my friend Annabeth on vacation in Washington, D.C. She was wearing jeans and a denim jacket over her orange Camp Half-Blood T-shirt. Her blond hair was pulled back in a bandanna. She was standing in front of the Lincoln Memorial with her arms crossed, looking extremely pleased with herself, like she'd personally designed the place. See, Annabeth wants to be an architect when she grows up, so she's always visiting famous monuments and stuff. She's weird that way. She'd e-mailed me the picture after spring break, and every once in a while I'd look at it just to remind myself she was real and Camp Half-Blood hadn't just been my imagination.