Dick and Nicole Diver are a sparkling 1920’s expatriate couple with two small children. They are whiling their life away on the French Riviera. Dick is a psychiatrist who, when we first meet him, is not practicing. Nicole had been his patient at an exclusive clinic where she had been admitted after a "nervous breakdown" (schizophrenia) occasioned by an episode of incest with her father.

The first section of the book presents the Divers through the eyes of Rosemary Hoyt, a young actress who is vacationing with her mother and develops an ambiguous relationship with Dick. Later, in a long flashback section, we learn the story of Nicole’s illness and treatment, culminating in Dick’s marriage--with the support of her family--to the incredibly wealthy Nicole. In the interest of Nicole’s health, her sister (“Baby”) helps Dick purchase an interest in the clinic. The remainder of the novel describes a gradual role inversion, whereby Nicole grows strong, healthy, and sympathetic; while Dick gradually weakens, succumbs to alcohol, divorces Nicole, and is finally left drifting from practice to practice in upstate New York.