Senior project engineer Kratina is known to be a very capable man. His colleagues have a feeling that his dealings may not always be legal but since they all profit from the bribes, they back Kratina. Kratina's machinations with loft flats and small family houses provide a high living standard for him and his young wife Ivanka. But then Kratina's frauds are uncovered by a man who blackmails the engineer over the phone and asks for money in exchange for keeping silent about what he knows. In the evening, Kratina deposits the bribe money following the blackmailer's instructions, and then hides in his car parked not far from there, waiting with a rifle in his hand. Instead of the blackmailer, he shoots Jirka, the young son-in-law of the cloakroom woman Helena from the near-by wine bar. Her friend, an old pianist Tuma cannot understand the murder and begins his own private investigation.