Hélène, a young widow, and Jean have pledged their love to each other, but are not engaged to marry. Their love affair allows dalliances with others, but they have promised to put each other first above all others. Hélène has been warned by a friend that Jean's love for her has cooled and fears this is correct. She tricks him into confessing, by pretending her own feelings for him have cooled to a friendship. She hides her shock and dismay when he enthusiastically accepts her as now just a friend instead of a lover. After he leaves her apartment, it is clear that she is devastated. But instead of mourning her love, she decides to exact a cruel revenge on him. The screenplay is by Bresson and it is a modern adaptation of a section of Denis Diderot's Jacques le fataliste (1796). Dialogues are by Jean Cocteau.