Percy Jackson goes on a dangerous quest to rescue Annabeth, who has been kidnapped, and to find the missing goddess Artemis. A prophecy warns that someone in the group may die during the mission.
Percy travels across the United States with Thalia, Grover, and Artemis’s Hunters, facing many monsters sent by the Titans. They discover that the Titan Atlas is responsible for Artemis’s capture.
During the journey, Bianca di Angelo dies while trying to protect her friends. Later, Percy helps defeat Atlas by temporarily holding up the sky, allowing Artemis and Annabeth to be saved.