One night, two of the mightiest gods from Greek mythology meet atop the Empire State Building. Zeus confronts Poseidon's son of stealing the master bolt, the source of his storm-making powers. He gives his sea god counterpart two weeks to return the artifact or face civil war. Poseidon's son is the troubled 12-year-old Percy Jackson, who grew up never knowing his father or his link to the gods of myth. During a field trip to an exhibition on Greek and Roman art, Percy is separated from his group by a Fury and questioned fruitlessly about the missing bolt. He is saved by his Latin teacher, Mr. Brunner, who is actually the legendary Centaur, Chiron. The centaur sends Percy to Camp Half-Blood, a camp for demigods, in order to train him control his powers.
At the camp, Percy is introduced to Luke, son of Hermes, and Annabeth, daughter of Athena. His training is cut short, however, when Hades kidnaps Percy's mother, Sally, demanding the master bolt as ransom. Percy launches a rescue attempt that pits him against Lotus Eaters, Medusa, a Hydra and the forces of the Underworld, finally making it to Hades to explain that he does not possess the master bolt. A fight ensues and it's discovered that Percy does inadvertently have the bolt, but hidden away inside the shield he borrowed from Luke, the true thief. Luke wanted the master bolt to overthrow the ancient gods and install a new generation of rulers over Olympus. The two fight with Percy coming out victorious and returning the bolt to its rightful owner, Zeus.