When demonic cheerleaders invade his high school, Percy Jackson hurries to Camp Half Blood, from whence he and his demigod friends set out on a quest through the Labyrinth, while the war between the Olympians and the evil Titan lord Kronos draws near.

Boone and his younger sister Heather are excited about spending the summer at Camp Hither, and at first they dismiss the horror stories about snakes that one camper is spreading, but then strange things start happening.

"Justin is going to start fourth grade-but first, he has to survive the summer. He "gets" to go to camp every day on a bus. He "gets" to experience all sorts of new things: Bugs. Mess hall food. Flip-flops (they hurt the space between his toes and they're hard to walk in). And (gulp!) swimming. Justin's little sister, Elizabeth, seems to deal with camp just fine. So do his friends. Justin is trying very hard not to be a worried kid anymore, especially...

Demigod Percy Jackson, still with no memory, and his new friends from Camp Jupiter, Hazel and Frank, go on a quest to free Death, but their bigger task is to unite the Greek and Roman camps so that the Prophecy of Seven can be fulfilled.