Freshwater centres around a young Nigerian woman, Ada, who develops separate selves within her as a result of being born "with one foot on the other side." Ada begins her life as a troubled baby and a source of deep concern to her family. When she comes of age and moves to America for college, the group of selves within her grows in power and agency. As Ada fades into the background of her own mind and these selves move into control, her life spirals in a dark and dangerous direction. Freshwater explores the metaphysics of identity and mental health, plunging the reader into the mystery of being and self.