When Camp Half-Blood, the only safe haven for demigods, comes close to being overrun by mythological monsters, Percy must find his best friend Grover, who is prisoner on an island in the Bermuda Triangle, and then set out to save the Camp.

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...

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. Percy soon discovers there is trouble at Camp Half-Blood: the magical borders which protect Half-Blood Hill have been poisoned by a mysterious enemy, and the only safe haven for demigods is on the verge of being overrun by mythological monsters. To save the camp, Percy needs the help of his best friend, Grover, who has been taken prisoner by the Cyclops Polyphemus on an island somewhere in the Sea of Monsters, the dangerous waters Greek heroes have sailed for millennia-only today, the Sea of Monsters goes by a new name?the Bermuda Triangle. Now Percy and his friends-Grover, Annabeth, and Tyson-must retrieve the Golden Fleece from the Island of the Cyclopes by the end of the summer or Camp Half-Blood will be destroyed. But first, Percy will learn a stunning new secret about his family-one that makes him question whether being claimed as Poseidon's son is an honor or simply a cruel joke.

You can't tell by looking at me that my dad is Poseidon, God of the Sea. It's not easy being a half-blood these days. Even a simple game of dodgeball becomes a death match against an ugly gang of cannibal giants - and that was only the beginning. Now Camp Half-Blood is under attack and, unless I can get my hands on the Golden Fleece, the whole camp will be invaded by monsters. Big ones . . . 'Puns, jokes and subtle wit, alongside a gripping storyline.' Telegraph