Claude Langmann, commissaire priseur quinquagénaire, forme avec Marie (Fanny Ardant) un couple uni depuis quinze ans et toujours aussi amoureux. Pourtant, dans l'intimité, et malgré un désir toujours vivace, Claude a des problèmes d'érection. Alors que Marie s'accommode en souriant de ces défaillances, Claude s'angoisse et décide de consulter un spécialiste. S'ensuivent divers examens médicaux dont Marie se moque gentiment. Pour se rassurer, Claude décide de séduire d'autres femmes. Lors d'un déplacement professionnel à Genève avec son ami Paul-Édouard, il se procure la nouvelle pilule Viagra, mais sa tentative de séduction est contrariée par sa fille. À son retour à Paris, de fil en pilules...

This French romantic comedy-drama concerns Claude Langmann, a middle-aged auctioneer, who is in a loving marriage with his second wife of 15 years. Though he is deeply in love with his wife and has remained faithful to her, he finds himself unable to perform in bed. His wife says she is satisfied with Claude's love and tenderness, but he visits a sex specialist anyway. There he learns of Viagra, which is not yet approved in France, though it is available in Switzerland over the counter. Soon Claude is on his way to Geneva, and eager to prove his manhood, tries to bed Agnes, his very attractive and very available assistant. His daughter, who also comes along for the trip, interferes with her own problems.