After learning that he is the son of a mortal woman and Poseidon, god of the sea, twelve-year-old Percy is sent to a summer camp for demigods like himself, and joins his new friends on a quest to prevent a war between the gods.
When Percy Jackson, a seventh-grade demigod living in New York, learns from his friend Annabeth that someone has poisoned the magical borders that protect Camp Half-Blood, Percy and his friends must journey into the Sea of Monsters to save their camp.