While in Italy, Marie falls madly in love with a charming surgeon, Xaver Gruber of Vienna. This worries her friend Hannah, who has sworn off men after her divorce. Xaver, who is afraid of serious relationships and prefers short affairs, gives Marie someone else's business card. Marie's passionate letters are delivered to this complete stranger, the nice but chaotic French mechanic Xavier Martin, who also lives in Vienna. After seeing her picture, Xavier falls hopelessly in love with Marie. Hannah, who wants to end Marie's agony, convinces her to get to the bottom of things. Xavier is surprised, and in an attempt not to disappoint Marie, introduces himself as "Louis Lefort," claiming that his friend Xavier is away. Hannah immediately falls in love with "Louis," unaware that she is interfering with Xavier's love for Marie. Turbulent days full of mix-ups, longing and unrequited love climax in a jumble of misunderstandings.