This time the two inspectors Herbert Schmücke  and Schneider have to investigate the mysterious death of restaurant-owner and painter Jens Dallman , whose body is found one day by his girlfriend Katrin Kreuzer in the central courtyard of the apartment they share. During the course of the investigation it emerges that a number of people had a possible motive. Kathrin Kreuzer had a violent argument with Dallman - partly about money - just before his death.  Building contractor Hans Schlüter also had reason to want Dallman out of the way, since Dallman was intending to sell a copy of the painting “Sonja” by Christian Schaad for him, passing it off as an original. And Schlüter’s own son Osswald had been hoping to trick his father out of the proceeds from the sale, since he needed the money to pay off some massive gambling debts.  As if this weren’t enough, Jens Dallmann had also been a witness to the robbery of a gas station.