Mika, heiress to a Swiss chocolate company, is married to celebrated pianist André and stepmother to his son, Guillaume, whose mother died in a car wreck on his tenth birthday. Their lives are interrupted by the unexpected arrival of Jeanne, a young woman who has learned she was almost switched with Guillaume at birth.

Louise has been a widow for years and teaches literature in a high school. She divides all her time between books and her son, Martin, who still lives with her. During a family lunch, she meets Martin's best friend, Stanislas, a young painter of Russian origin, who is studying at the Beaux-Arts and whose talent promises a brilliant career. Louise is still finding Stanislas very attractive and already the young man is madly in love with her. All it takes is a little something to bring the two lovers together in the same passionate embrace. Informed by his mother, Martin pretends to be delighted by this unexpected rapprochement between the two beings he loves the most. His rage bursts, however, during the family meeting that Louise has organized to make her affair with Stanislas official.

Anna, a somewhat introverted woman, becomes obsessed with the orthopedic surgeon who helped with her recuperation following a car accident. Incorrectly believing the love to be reciprocated, she embarks on several attempts to try and stay in touch with him but, after several rejections, finds herself descending into despair and, ultimately, hatred.

Jacques asks a public writer to compose love letters for a beautiful stranger that he pretends he has just met.