Heroes of Olympus (The Son of Neptune) (Rick Riordan) [paperback]

The Son of Neptune is the second book in The Heroes of Olympus series by Rick Riordan. It follows Percy Jackson, who has lost his memory, as he arrives at Camp Jupiter, the Roman counterpart to Camp Half-Blood. He meets two new demigods: Hazel Levesque, a daughter of Pluto, and Frank Zhang, a son of Mars. Together, they embark on a dangerous quest to stop the giant Alcyoneus from rising and prevent the Earth goddess, Gaea, from waking.

Percy, Hazel, and Frank must journey to Alaska, the land "beyond the gods," where they face deadly enemies, harsh conditions, and the looming threat of Gaea’s forces. Along the way, they learn to trust each other and unlock their own unique powers. Hazel must confront her dark past, and Frank must come to terms with his mysterious ancestry and the fragile nature of his life.

The novel explores themes of memory, identity, and destiny, as Percy struggles to regain his lost memories and remember who he truly is. It also delves deeper into Roman mythology, expanding the universe of the series by introducing new characters, powers, and Roman gods, while setting the stage for the larger conflict between the forces of Gaea and the demigods.