The Sea of Monsters (Percy Jackson and the Olympians #2)

After a summer spent trying to prevent a catastrophic war among the Greek gods, Percy Jackson finds his seventh-grade school year unnervingly quiet. His biggest problem is dealing with his new friend, Tyson—a six-foot-three, mentally challenged homeless kid who follows Percy everywhere, making it hard for Percy to have any "normal" friends. But things don't stay quiet for long...