When Rose was 12, her mother and stepfather went out for dinner and never came back. Now 17, she lives with her grandmother and goes to school in London. She's always wondered about her stepbrother, Joshua, who she only lived with briefly and who was also relocated after their parents' disappearance. When Rose and Joshua meet again, they find they have much in common, including a desire to uncover the mystery surrounding their parents' disappearance . . . and a mutual passion for each other. But what they discover as they begin searching is that a much larger conspiracy—The Butterfly Project—is underway, one that puts both their lives in danger.