Set in the pre-insulin 1920s, Sugar Water follows the parallel lives of a Canadian researcher named Frederick G. Banting and 13-year-old American girl named Guinivere Cluss. While on a family vacation, Guinivere is plagued by gnawing thirst and hunger. She drinks, eats, and urinates at alarming rates. After boiling her urine and finding granules of sugar, a doctor diagnoses Guinivere with juvenile diabetes. She is enrolled at a clinic known for using extreme measures to prolong patients' lives. Put on a grueling starvation diet, Guinivere struggles for the will to live. Through her difficult convalescence, she learns how deal with her family as they begin to treat her differently, rebels against the inevitable result of diabetes, and to hopes for a miracle. Meanwhile, Dr. Frederick G. Banting embarks on a path with no foreseeable future and myriad pitfalls: after a year of struggling medical practice in sleepy London, Ontario, Banting begins researching diabetes at Toronto University. With the help of Charles Best and Dr. J.R.R. MacLeod, Banting tests his theories on hundreds of laboratory dogs, hoping to find fame and a solution to the mysterious disease. Sugar Water ends with the converging lives of Guinivere and Dr. Banting, and the miraculous discovery that saves them both.