It’s a good thing the girl holding his hand knows his name, because until she says it, Jason has no clue what it is. He doesn’t know who she is, either, or the short kid with the busy hands and sarcastic mouth. In fact, he doesn’t remember anything about his life.

The girl—his girlfriend, apparently—is Piper McLean. The short kid—his best friend, apparently—is Leo Valdez. They’re on a school field trip to the Grand Canyon led by a gruff baseball-bat-wielding guy named Coach Hedge.

Jason also discovers a few other key things. One: Dylan, an annoying boy on the bus who wants to get with Piper, is actually an annoying storm spirit who wants to kill him. Two: The gold coin in his pocket can turn into a gold sword. And three: The gold sword is quite good at disintegrating annoying storm spirits.

Oh, and there’s one more thing: He can fly.

Beyond that? Not a clue.

Luckily, a girl with answers—and a pegasi-drawn chariot—arrives on the scene. Her name is Annabeth Chase, and she’s looking for someone named Percy Jackson. But he’s not there, and Piper and Leo have never heard of him. Annabeth covers her disappointment and takes Jason, Piper, and Leo to a safe place called Camp Half-Blood.

Jason has no trouble believing what Annabeth says about them being demigods. And Camp Half-Blood seems like a great place for kids like him. Except . . . he can’t shake the feeling he doesn’t belong there, not even when he’s claimed by Zeus—or Jupiter, as Jason can’t help thinking of the sky god.

Meanwhile, Piper is having issues, too. A red-haired girl named Rachel Elizbeth Dare—the Oracle of Delphi, Annabeth says—was possessed by Hera right in front of her. In Hera’s voice, she warned about the fiery giant Piper has been seeing in her nightmares. Then she commanded Piper to find her and free her.

Leo got off to a better start, being claimed by the god Hephaestus almost immediately. But he had a spooky moment of his own when he caught a glimpse of a freaky old lady from his past. What she was doing at Camp Half-Blood, he didn’t want to know. He’s more interested in exploring the forges and learning about the bronze mechanical dragon terrorizing the camp.

Despite their problems, Jason, Piper, and Leo are ready to settle into camp life. But it is not to be. That night, Rachel issues a prophecy that calls for three demigods, a child of Zeus, a child of Hephaestus, and a child of Aphrodite, to go on a quest to save Hera from her imprisonment. Jason, son of Zeus, is the leader. Leo volunteers to go along. He’ll even provide their ride, the newly rebuilt bronze dragon named Festus. When Piper is claimed by Aphrodite, the trio is complete.

They leave the next morning, riding Festus and following the wind to find clues that will lead them to Hera. Unanswered questions go with them. Who is Jason Grace? Who imprisoned Hera, and more importantly . . . why?