Young Kuttel belongs to a group of working-class children who live in Berlin at the beginning of the 1930s. In the big summer holidays in 1931, the children want to make a race with their model boats and choose as a venue for the small artificial water in the park of their neighborhood. All children in the area are invited to participate in the competition. But there is a traitor among them, who tells the company to the local police officers, who in any case look with arrogance on the "Reds"...

At the end of the 1950s, the production of optics in the German Democratic Republic has reached top quality and instigates interest in the West. When national demand rises strongly and at the same time the export to South America heavily decreases, the Volkspolizei - the GDR police force - starts to look into the case. Two seemingly unrelated cases are the starting point for the investigation by second lieutenant Schellenberg of the department for optics racketeering: An old woman who was arrested in the Berlin city railway for trying to smuggle a pair of binoculars to West Berlin, and a dead person in an area of allotments who was involved in obscure dealings with optical devices.