Stanek, a truck driver, is working on a large construction site far from Prague. He hasn't been home for several weeks and is tormented by the idea that his wife is unfaithful. So he sets off to Prague underground and has many adventures along the way. He is stopped by a policeman just outside the building and gives a lift to a group of young people, where he is attracted by a charming girl, a single mother... At home, however, he does not find his wife Ruzena and finally succumbs to the seductions of a neighbour whose husband has left for the night shift. On his way back to the building site on a foggy night, he meets a broken-down ambulance, in which the girl from the youth group who attempted suicide is a patient...