A young boy named Percy Jackson (Logan Lerman) discovers that he is the demigod son of the Greek god, Poseidon (Kevin McKidd). He embarks on a journey across modern-day America with his friends Annabeth Chase (Alexandra Daddario), also a demigod, and Grover Underwood (Brandon T. Jackson), a satyr, to save his mother (Catherine Keener), return Zeus' (Sean Bean) stolen lightning bolt, and prevent a war between the gods.