: Son of Poseidon ; he struggles with the weight of a prophecy while trying to prove himself a capable hero.
: The core motivation for the quest is Percy's refusal to leave his friend Grover behind.
The story begins with Percy Jackson having nightmares about his friend Grover Underwood being hunted. Shortly after, Percy discovers that the magical tree protecting Camp Half-Blood—formed from the spirit of the demigod Thalia Grace—has been poisoned, leaving the camp vulnerable to monster attacks.