Being outcasts themselves at Camp Jupiter, Frank and Hazel empathize with Percy's outsider status and consider it their duty to help him adjust and acclimatize quickly to the camp's routines and leadership. Octavian tells Percy that the Book of Prophecies is missing. He quickly befriends the guards, Frank Zhang, son of Mars and Hazel Levesque, daughter of Pluto, and subsequently gets introduced to the praetor of the camp, Reyna, and the augur Octavian, who quickly takes a dislike to Percy. She tells him privately that he can only regain his memory by learning to be a hero again and successfully survive the challenges he encounters at camp. Having been protected by Percy during the attack, Juno announces Percy's arrival with approval, identifying him as a son of Neptune. Upon arriving, he is attacked by several Gorgons - Stheno and Euryale - and successfully defends a disguised goddess Juno and the camp with the help of the guards on duty.

Under the initial guidance of Lupa, the wolf-goddess and protector of ancient Rome, he makes his way toward Camp Jupiter, the Roman demigod training camp and counterpart to the Greek demigods' Camp Half-Blood. Nine months after Percy Jackson's defense of Mount Olympus in The Last Olympian, Percy finds himself alone and on the run from monsters in southern California without his memories.

The son of neptune