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.

A socialist story of "atoms for peace" and compulsory labor in an East German uranium mine under Soviet control.

The film tells the love story of two young couples. According to their social ranks, construction worker Edy is dating employee Siegi, while medical student Dieter is dating art school student Sonja. Rather unintentionally, they exchange partners. During a carnival ball, Dieter makes out with Siegi because he falls for her her fresh and happy girlish manner. Sonja coolly observes this game and sees this intermezzo as a test for their relationship. While Siegi and Dieter vacation at the sea, Sonja falls in love with Edy. Now the die seems to be cast for new constellations. But when both couples stand in front of the registrar’s office, they finally come to their senses.

In a small town, a brigade is working on the construction of a new cultural center. Gerhard loves Karin, the daughter of brigadier Franz, who is not thrilled with the prospective son-in-law. Under the influence of his colleague "Boxer", who wants to go to a big city with him, Gerhard neglects his crane operator course, his work and ultimately Karin too. The failed crane test infuriates him and turns him into a rioter. After quarrels on the construction site, Franz is found unconscious on the crane at night. Gerhard comes under suspicion, but the accident was the fault of "Boxer". When he tries to escape, Gerhard, who has come to his senses, is able to hold him back. Remorseful, they go to the police together. Karin is also reconciled and the wedding is to take place in the finished Kulturhaus.