A foolproof business

The owner of a bicycle store is found dead in his store by his girlfriend Steffi and his employee Tom Lehnert. Steffi's ex-boyfriend quickly becomes the suspect of Beissl and Jerry. He apparently hasn't gotten over the breakup and is stalking the new couple. The dead man also owed a friend a lot of money, which he demanded back shortly before his death. But it is not until the detectives take a closer look at Tom Lehnert's past that they get on the tracks of the murderer.