After a summer spent trying to prevent a catastrophic war among the Greek gods, Percy Jackson is finding seventh grade unnervingly quiet. His biggest problem is dealing with his new friend, Tyson, a six-foot-three, mentally challenged homeless kid who follows Percy everywhere. But things don't stay quiet for long. Percy soon discovers that there is trouble at Camp Half-Blood: the magical borders that protect Half-Blood Hill have been poisoned, and...

"Mason and Ty were once the very best of friends, like two nerdy sides of the same coin . . . until seventh grade, when Ava Petrakis came along. Now Mason can trace everything bad in his life to that terrible fight they had over the new girl. The one thing he'd give anything for is a do-over. But that can't happen in real life--can it? As a science kid, Mason knows do-overs are impossible, so he can't believe it when he wakes up from a freak accident...