Bernd Neubauer is Professor of History in Berlin. He specializes in the history of the Federal Republic of Germany. His wife Lena recently moved in with him from Bavaria. They have a happy and harmonious marriage. During his long-distance relationship with Lena, however, Bernd had started an affair with the waitress Melanie. For Bernd, however, it is no problem to reconcile both relationships. During a trip to the state of Brandenburg, Bernd and Lena discover a quaint, old house that they fall in love with. The old Mrs. Maschke has lived here since her childhood. Now she is a widow and alone. Bernd and Lena buy the house from her and grant her lifelong right of residence. Now Bernd only needs one child for the perfect life. He wants the child from Melanie, who would rather keep her independence. Nevertheless, she hopes that Bernd will eventually separate from his wife. Bernd, however, feels very comfortable in his situation. As an early riser, he leaves the matrimonial bed early in the morning and meets Melanie for breakfast. When Lena finally suspects that Bernd is hiding a secret, she follows him in a taxi one of these mornings. She confronts Bernd with her suspicions and he confesses the affair with Melanie. A child is now supposed to save the marriage with Lena. Lena did not get pregnant for years. Now the couple goes to a doctor to check Bernd's fertility. The relationship with Melanie becomes more difficult now that he is under constant observation by Lena. When Melanie wants to take up a job offer to Hamburg, they end their relationship. Bernd does not want to admit this, but looks forward to a joyful future with Lena in the newly renovated house. During the renovations, wife Lena spends a night of love with polish worker Andrzej, while Bernd has a working meeting with an Israeli history professor. Melanie and her best friend Linda also appear at the inauguration ceremony of the house. From Linda, Bernd learns that Melanie is pregnant. At his next visit to the doctor, however, Bernd receives the diagnosis that he is unable to conceive. When he comes home confused, he learns that his wife Lena also has happy news for him. She is also pregnant.