Thalia's tree, the magical border of Camp Half-Blood, has been poisoned. Chiron is blamed for the poisoning and is dismissed from camp; Tantalus, who comes from the Fields of Punishment and cannot have food or water, takes the job. The only thing able to rid the tree of its poison is the Golden Fleece, which is located on the island of Polyphemus (another son of Poseidon), in the Sea of Monsters (the Bermuda Triangle).