From the days of her childhood in the 1950s Midwest, Katherine knows she is different, and that her parents are not who they seem. As she matures from a girl of rare intelligence into an exceptional mathematician, traveling to Europe to further her studies, she must face the most human of problems--who is she? What is the cost of love, and what is the cost of ambition? These questions grow ever more entangled as Katherine strives to take her place in the world of higher mathematics and becomes involved with a brilliant and charismatic professor. When she embarks on a quest to conquer the Riemann hypothesis, the greatest unsolved mathematical problem of her time, she turns to a theorem with a mysterious history that may hold both the lock and the key to her identity, and to secrets long buried during World War II. Forced to confront some of the most consequential events of the twentieth century and rethink everything she knows of herself, she finds kinship in the stories of the women who came before her, and discovers how seemingly distant stories, lives, and ideas are inextricably linked to her own.