Several murders of young girls have been committed in the regional center, the result of the investigation of which leads detectives to the conclusion that a maniac is operating in the city. In order not to cause panic among the population, this version is not officially announced, but work on it is being carried out with all the forces of the regional criminal investigation department. At the same time, a team of private detectives is trying to understand the intricacies of the family relationships of the spouses, who are also friends of the private detective Osokin. As a result of a private investigation, it becomes clear how ordinary adultery can lead to a series of dangerous crimes, including murder.