Set in Rhode Island , it tells the story of a 13-year-old girl named Anna Fitzgerald , a `` designer baby '' , who sues her parents so that they can no longer legally control her medical decisions once she learns expected to donate a kidney to her older sister Kate , who is dying from leukemia , cancer of the blood and bone marrow . It tells the story of 13-year-old Anna , who litigates her parents for medical emancipation when she is expected to donate a kidney to her sister Kate , who is dying from leukemia .