Cleavage tracks the patchwork musings of Leah, who, at twenty-four years old and two years into a relationship, discovers she has breast cancer. Told in fragments reminiscent of A Complicated Kindness by Miriam Toews, Cleavage details Leah's struggles with her illness and treatments, the conflict between her disease and her boyfriend, her ambivalence toward her job, and a long-standing feud with her mother and only sister.