After the death of her mother Marianne, a young cellist discovers that her father had a mistress. In order to find her, she casts aside her boyfriend Étienne. The mistress is a pianist named Béatrice. Béatrice and Marianne strike up a friendship while reminiscing about the past. They remember Édith Piaf's song : "Hymne à l'amour" and Marianne reconnects with her nanny Ghislaine who was a funny companion when she was young.