In the winter of 1889, the murder of General Shtrundman and her maid occurs in St. Petersburg. Suspicion falls on the footman, but detective Mechislav Kuntsevich, thanks to a hat box found in the apartment, leads to the alleged murderers. The girl with whom Kuntsevich is in love may well be an accomplice. The behavior of this pretty hat shop saleswoman arouses a lot of suspicion. And when, during the investigation, the detective finds out that the criminals who killed the general’s wife committed another murder - the actress Marseilles, he has to take a serious look at the girl who turned his head.