A hidden daughter of Zeus living a peaceful life on the California coast has spent years raising her little brother, Dally, after their neglectful mother failed them. When Dally, now a son of Apollo at Camp Half-Blood, has a terrifying vision that his sister is in danger, he runs away to find her. Chased across the country by the Seven, Nico, Will, Reyna, and Thalia, they arrive at a sunny beach expecting to retrieve a scared child—only to discover a breathtaking surfer girl whose emotions seem to command the sky itself. As monsters begin to attack and storms rage overhead, the truth comes to light: Zeus has another child, one hidden from Olympus for seventeen years. Now, Y/N must uncover why she was kept secret while navigating newfound powers, dangerous prophecies, and an unexpected connection with Reyna.