Tyson (Percy Jackson)
Thalia's tree, the tree which serves as the magical border of Camp Half-Blood, is mysteriously poisoned. Chiron is blamed for poisoning the tree and dismissed from camp; Tantalus takes his job. The only thing able to cure the tree is the Golden Fleece, which has healing powers for plants, animals, and humans. It is located on Polyphemus's Island in the Sea of Monsters (the Bermuda Triangle).