Cassia lives in a society that matches people and strictly controls nearly every aspect of life. She is matched with her friend Xander but is drawn to Ky, an "aberration" who was not supposed to be matched. Cassia begins to question the society and rebels through small acts like not taking her medication. She and Ky develop secret feelings for each other while learning about the history and culture that the society has banned. Cassia risks everything to help free both Ky and herself from the oppressive controls of the society.