Jochen Bähr, department head in a pharmaceutical company, is found shot dead in his boat early on a Sunday morning. At the crime scene is his young son Thomas, who is in shock and unable to speak. Schimanski, who needs the boy's statement, tries to break his encapsulation. He has initial success - then Thomas is kidnapped under the eyes of the inspector.

This time the crime scene is an Italian restaurant in Duisburg. Schimanski happens to witness an armed robbery of the landlord Giovanni Salvatore. He intervenes and experiences a fiasco: his girlfriend Renate is pushed into the line of fire by one of the gangsters and dies. Knowing that he has killed an innocent person, he puts down his weapon. Thanner joins the manhunt for the two perpetrators and pays dearly for it: Schimanski finds him unconscious, with serious injuries, after a car accident.

A murder in connection with illegal art trading leads - shortly after the fall of the Wall - to the first East-West contacts in the field of crime. Schimanski and Thanner investigate together with their popular colleagues Fuchs and Grawe from East Berlin: paintings owned by the GDR, which were extorted from museums and private individuals in the course of obtaining foreign currency, were put aside by former Stasi employees after the fall of the Wall and are now to be sold to the West via the old channels. The police suspect the Düsseldorf-based art dealer Schrader to be the key figure.