This crime drama from the former Czechoslovakia begins with a murder of a woman in close proximity to a factory run by chief engineer Kral. Kral is a notorious womanizer, and is a strong suspect until he produces an airtight alibi. Once he is eliminated from the enquiry, many possible motives for the murder present themselves, including that of his marriage-minded current mistress. But things become more complicated when she also finds the perfect alibi.