When Nixie Jackson, the forgotten daughter of Hades, crosses paths with her older brother Percy during his quest in the Underworld, her carefully constructed afterlife begins to unravel. Haunted by fragmented memories of a life she doesn’t remember, Nixie escapes the shadows of her father’s domain and finds herself at Camp Half-Blood. As she struggles to adjust to a world of sunlight, heroes, and new friendships, Nixie must uncover the truth about her past—and decide whether she belongs with her brother among the living, or back in the darkness she once called home.