Iliana López was adopted by Sally Jackson when she was 4-years-old. She was there when her brother, Percy Jackson, found out who his father was. He was there when she found out who HER father was. Adopted or not, they were siblings. She was also there when her brother disappeared. Iliana, now 14, goes on a quest with Jason Grace, Piper McClean, and Leo Valdez, to look for him. What will happen?