After Camp Half-Blood's protective border is breached, Percy Jackson embarks on an epic odyssey into the Sea of Monsters in search of his best friend, the satyr Grover Underwood, and the one thing that may save the camp — the legendary Golden Fleece. Aided by demigods Annabeth Chase and Clarisse La Rue, along with his cyclops half-brother Tyson, Percy's survival becomes the key to preventing Luke and the Titan Kronos from bringing down Camp Half-Blood — and, ultimately, Olympus.