Případ dvou sester.

Captain Vašátko of the criminal police and Horác, a painter, bohemian, and amateur detective, are searching for the murderer of Daniela Jásková, an emancipated young woman who excelled at her job and also excelled at changing lovers. When she is found strangled in her apartment, Vašátko's team begins an investigation. They also focus on the victim's sister, Alena Kášová, who did not like Daniela very much and resented her ability to win over every man. Suspicion also falls on Alena's ex-husband, the sculptor Káš, whom Horác has known since his studies at the academy.