Synopsis

The murder of Chief Inspector Ann Kathrin Klaasen's father 15 years ago is affecting her. She runs into an old lady, named Gertrud Klocke, who is carrying a photo of her father with a woman. Gertrud tells her that the man in the photo is her daughter Isolde Klocke's fiancé. Soon, Gertrud is found dead. Isolde, a police sergeant, working as an undercover with Ann's father, investigated a human trafficker. Ann contacts his father's former partner Wilhelm Beukelzoon, who is living a new life under a witness protection program. He accuses her father of leading a criminal double life. Just as Isolde tells Ann that the bank robbery, in which his father died, was just a cover, Isolde is shot by a professional killer. There must be someone in the police who does not want the truth to come to light. A lawyer Heiko Käfer is involved, as well as Friedhelm Stenger. After Ann visits Stenger and Käfer respectively, they are killed. When she realizes that her father is innocent and that Beukelzoon is her father's murderer, she arrests him. Ann is relieved that her father had to die because of the evidence he collected against the human traffickers. He kept it in a safe deposit box. His opponents wanted to get hold of these documents by robbing the bank, but they failed.