Dick and Nicole Diver are a glamorous couple who rent a villa in the South of France and surround themselves with a coterie of American expatriates. Rosemary Hoyt, a 17-year-old actress, and her mother are staying at a nearby resort. Rosemary becomes infatuated with Dick and becomes close to Nicole.
Rosemary senses something is wrong with the couple, and her suspicions are confirmed when another guest at a party, Violet McKisco, reports witnessing Nicole's nervous breakdown in a bathroom. Tommy Barban, another guest, comes to the defense of Nicole and insists that Violet is lying. Angered by this accusation, Violet's husband Albert duels Barban on the beach, but both men miss their shots. Following these events, Dick, Nicole, Rosemary, and others depart the French Riviera.
Soon after, Rosemary is now a constant companion of both Dick and Nicole in Paris. She attempts to seduce Dick in her hotel room, but he rebuffs her advances, although he admits that he loves her. Much later, a black man named Jules Peterson is found murdered in Rosemary's bed at the hotel, a potential scandal which could destroy Rosemary's career. Dick moves the blood-soaked body out of the room to cover up any implied sexual relationship between Rosemary and Peterson.
A flashback occurs in the narrative. In Spring 1917, Dick Diver—a promising young doctor—visits psychopathologist Franz Gregorovius in Zürich, Switzerland. While visiting Franz, he meets a patient named Nicole Warren, a wealthy young woman whose sexual abuse by her father has led to mental neuroses.[c] Over a period of time they exchange letters. With the permission of Franz who believes that Dick's friendship benefits Nicole's well-being, they start seeing each other. As Nicole's treatment progresses, she becomes infatuated with Dick who, in turn, develops Florence Nightingale syndrome. He determines to marry Nicole in order to provide her with lasting emotional stability.
Don't you worry I surrender Days are long and life's a bender Still I know that Tender is the Night.
—F. Scott Fitzgerald[15]
Dick is offered a partnership in a Swiss psychiatric clinic by Franz, and Nicole uses her finances to pay for the enterprise. After his father's death, Dick travels to America for the burial and then journeys to Rome in hopes of seeing Rosemary. They start a brief affair which ends abruptly and painfully. A heartbroken Dick is involved in an altercation with the Italian police and is physically beaten. Nicole's sister helps him to get out of jail. After this public humiliation, his incipient alcoholism increases. When his alcoholism threatens his medical practice, Dick's ownership share of the clinic is purchased by American investors following Franz's suggestion.
Dick and Nicole's marriage disintegrates as he pines for Rosemary who has become a successful Hollywood star. Nicole distances herself from Dick as his self-confidence and friendliness turn into sarcasm and rudeness towards everyone. His constant unhappiness over what he could have been fuels his alcoholism, and Dick becomes embarrassing in social and familial situations. A lonely Nicole enters into an affair with Tommy Barban.[d] She later divorces Dick and marries her lover.
