Benno, commissar in the Homicide Department Munich and married to forensic doctor Andrea, finds himself one day in a seemingly unsolvable, fatal situation again. His lover Sabine, who is ironically the wife of his superior, chief commissioner Hartmut, is found murdered in her sister, Martha's home. Benno is summoned to the scene in this murder case. Hartmut can not manage the investigation as a husband and thus transfers the case to Benno. All others come under suspicion for this: his wife, his father-in-law and the widower. Everyone had a motive, everyone was at the scene. But even Benno himself comes as a perpetrator in question: On the morning of the murder his lover had put an end to him.