"The Heir" is a young adult novel by Kiera Cass and is the fourth book in the Selection series. It follows the story of Eadlyn Schreave, the daughter of Maxon Schreave and America Singer, as she navigates her responsibilities as the future queen of Illea. Eadlyn is faced with the challenge of finding a suitable partner through a competition similar to her parents' experience. As Eadlyn embarks on her own selection process, she grapples with her feelings and the expectations placed upon her. The novel explores themes of love, duty, and self-discovery, highlighting Eadlyn's journey to understand her identity and the role she will play in her kingdom's future.