The year is 1941 and the German Nazis rule Bohemia with a free hand. Engineer Otakar Racek is an extremely cautious man who tries to avoid problems at all costs. While some of his colleagues are being arrested by the Gestapo, he receives an offer to become the director of a new department. When he refuses to help the wife of an arrested resistance fighter, his wife Vlasta is shaken. However, she loves him, to the point of even resigning herself to the hatred of Otakar's wealthy mother. One day, Vlasta lets her old acquaintance Ondřej Rýdl, who is on the run from the Gestapo, stay at her house for a few days. The wife passes him off to her husband as a distant relative. However, Otakar succumbs to jealousy and, on his mother's advice, hires a private detective to follow Vlasta. However, the detective is also a Gestapo informant and receives a hefty reward for every arrested resistance fighter...