In the Leipzig cheese dairy Dettmer, the driver Ludwig Noack is found dead in the disinfection chamber. Despite the best efforts of forensic scientists, no traces were found on the body. The chief inspectors Ehrlicher and Kain learn from the owners of the family business, the siblings Jörg and Katharina Dettmer, that their employee has recently been beaten up by Strasser, a debt collector. Katharina in particular is now convinced of this man as the perpetrator, but gets caught up in contradictions in her statements. The public prosecutor Mitterer presented them with another suspect: Klaus Röbel, convicted of the murder of Katharina Dettmer's daughter, was released early the day before.
Relevant to his conviction before sixYears ago, Noack's testimony, to which he threatened revenge in the courtroom. Ehrlicher and Kain find Röbel in the apartment of his partner Vera Bednarz. However, he denies killing Noack. Ehrlicher examines Röbel's cell, which fortunately has not yet been cleared, and learns that the ex-prisoner only met his girlfriend Vera in prison. It also turns out that Röbel and Strasser knew each other from prison and that Vera Bednarz has close contact with the Dettmer family. Ehrlicher and Kain suspect that there is a connection between the past crime against Katharina's daughter and Noack's death. When the junior boss of the cheese dairy, Jörg Dettmer's son Manuel, was suddenly kidnapped, the situation came to a head...