One day after returning home from his boarding school, Percy and his mother Sally Jackson, travel to a beach in Montauk. After a series of harrowing incidents, Percy finds out that he is a demigod son of Poseidonthe Greek god of water and that the gods are accusing him of stealing Zeus' master lightning bolt. To clear his name and save the world from another war between the Olympian gods, he sets out to find the real thief and retrieve the lightning bolt. Thus Percy Jackson and his companions, a satyr named Grover Underwood and Annabeth Chase, a daughter of Athena, start on a journey to the underworld, facing numerous mythological monsters on the way. After discovering Hades to be a victim of theft as well, they escape and retrieve the stolen goods from Ares. In the end, they learn that Luke Castellan, a camper of Camp Half Blood, and son of Hermes, was the real thief and had stolen the bolt to allow Kronos the king of the titans a chance to rise again.