The main characters include: Poseidon, Zeus, Medusa, Percy Jackson, Annabeth Chase, Grover Underwood, Luke Castellan, Chiron, and Clarisee La Rue. Percy Jackson is a demigod and the son of Poseidon. Poseidon is the God of the seas and Zeus is the God os the sky. Grover Underwood is Percy's personal protector, he is a satyr while Annabeth Chase is Percy's best friend. Percy, Grover, and Annabeth go on a mission together to get the lightning bolt back.
After school, Percy and his mom go to a nearby beach, only to have to leave because of a storm. During the storm, Percy is attacked by a Greek monster which he later kills shortly before falling asleep. When Percy wakes up, he is inside of camp half-blood where he find out he is the son of Poseidon. Percy gets sent on a quest by Chiron, the camp director, to find Zeus' stolen lightning bolt, that everybody thinks Poseidon stole. Percy is able to find the lightning bolt and return it to Zeus before he can start a war. Percy then returns to his school, and plans to go back to Camp Half-Blood the next summer.