Percy Jackson and the Olympians book 2

I have read Percy Jackson and the Olympians book two, The Sea of Monsters, by Rick Riordan. It is about seventh grade Percy Jackson who is always getting in scrapes with monsters. This time it is during a game of dodgeball when the player morph into a gang of ugly cannibal giant. When this happens Annabeth, Percy's friend, shows up bringing bad news about the camp, the magical border that  is protecting the camp is failing as a result of being poisoned. What will Percy and his friends have to do to save the only safe place for demigods?