Poul Henriksen is a bank teller, a man in his prime with a hobby of studying Napoleon. He is happily married to the lovely Mrs. Gerda, a devoted mother to their three children. She has long since learned that men always remain big boys, and she is therefore also a mother to her husband. Their son William is "something" in an office, which bores him terribly. Instead, he has thrown himself into jazz with fanatical zeal and dreams of becoming the greatest jazz musician of all time. William also has a girlfriend, Nina, who is enthusiastic about jazz and visits him at all hours of the day and night, which greatly concerns his parents. A conflict forces Poul to kick his son out of the house. This makes the parents unhappy, and on top of that, they have come to believe that William should have a child with Nina.