The story begins when Katharina Blum rings a door bell of Walter Moeding’s home. Since she knows that Walter Moeding is a crime commissioner, she comes to confess to murdering and to request to be arrested. A dead man is Werner Tötges, a reporter from the News who Katharina should thank for her ruined life and career. Although the police find one more body which belongs to Tötges’s colleague, Schönner, a press photographer from the News, Katharina has nothing to do with his death.
Katharina Brettloh Blum is born on March 2, 1947 at Gemmelsbroich in the district of Kuir. After her father’s death, the family starts suffering from the lack of money. In order to help her family, Katharina has to share with her mother the whole amount of house duties. However, it doesn’t prevent her from studying and getting pretty decent marks. Later on, Katharina begins working in the homes of her neighbors, learning how to cook, slaughter and clean properly. When she leaves school, her godmother Else Woltersheim helps her to get a position of a maid. Following her godmother’s advice, she enters and graduates from a home-economics school. Having a diploma in house-keeping she gets a chance to obtain better positions.
Katharina works a lot, getting needed experience and building a reputation of a perfect maid. When she meets the Blornas, they offer her work and a room at their house, but being an independent person she refuses to live with them. The Blornas help her to buy her own apartment and an idea of having her own place makes her very happy. Living extremely economically she helps her ill mother and brother. Katharina’s life doesn’t consist only of work, she used to be married, but the marriage proves to be a complete disaster. Katharina’s ex-husband Wilhelm Brettloh, according to Else Woltersheim, is a genuine ass-liker and a show-off. At Elsa’s party Katharina meets Ludwig Götten, who happens to be a wanted murderer, and falls in love with him. He stays at Katharina’s apartment for a night and then she helps him to escape. Hardly does she start her breakfast when the police officers enter her flat. Being accused of hiding the murderer and helping him to escape, she is taken to the police office.
The moment when the police officers lead Katharina to a car is captured by the Werner Tötges, the reporter from the News. Then the newspaper releases a series of articles dedicated to Götten’s case claiming that Katharina is his accomplice. Having interviewed several former employers of Katharina and people who are acquainted with her, he mostly misinterprets their words, portraying her as a marriage-breaker and a gold digger. The further these false accusations go, the more people get involved in the scandal. Out of sudden, Werner Tötges claims the Blornas are communists who help Katharina in her criminal activity.
When the police find in Katharina’s apartment an expensive diamond ring and a love letter, they try to persuade her to give them a name of a person who gives these gifts to her. The main reason of her silence is that these things are received from Alois Sträublender, a conservative politician, who is also known in the economical, political and academic world. He pursues Katharina, trying to woo her. Even if Katharina could tell others about Sträublender’s pursuing, people would hardly believe her.
Sträublender also gives Katharina a key to his house, where she is allowed to come. Instead of coming there, she gives than key to her dear Ludwig, so that he could hide there. The police officers find and arrest him there.
After the moment when the scandalous articles start appearing, Katharina starts behaving differently. Her dear Ludwig is arrested, her mother is dead, courtesy of Werner Tötges, who sneaks into the hospital and scares the poor woman who happens to be rather ill, her career is ruined and lots of people she used to know don’t want to have anything in common with her. So she decides to revenge Tötges. She calls him and promises to give an interview. When Tötges comes, he behaves frivolously and rudely, suggesting that she could sleep with him first. Katharina shoots him several times and then go to Moeding.