The widower Erwin Mai is a respected master craftsman in his company - energetic, active and full of ideas. At home, however, he likes to keep his nose clean. His sister Elsbeth, who runs the household, thinks he is a complete failure, especially when it comes to raising his two eleven-year-old offspring. And indeed, the twins Kalle and Kulle are beginning to go to seed. With their pranks, they gradually drive the teachers at school and their fellow adults in the neighborhood to despair. Aunt Elsbeth is understandably worried. She resolves to get Erwin married again as soon as possible. We can look forward to the result of her efforts, as not only Erwin's father but also his two brothers put up an energetic fight.