Percy Jackson is a good kid, but he can't seem to focus on his schoolwork or control his temper. And Percy could have sworn his pre-algebra teacher turned into a monster and tried to kill him. When Percy's mom finds out, she sends Percy to Camp Half-Blood, a summer camp for demigods, where he learns that the father he never knew is Poseidon, God of the Sea. Soon, a mystery unfolds and together with his friends, Percy sets out on a quest across the United States to reach the gates of the Underworld and prevent a catastrophic war between the gods.