The detective story takes place on Maslenitsa in St. Petersburg in March 1894. A series of crimes leads A. Pushkin to the insurance company "Stability". It turns out that the employees are involved in scams. The investigation leads to the family of the owner of "Stability" M.Alabyev. Pushkin's beloved A. Kern is involved in the war that unfolded between the children of Alyabyev and his wife Lydia. Thinking that he is investigating the case, Pushkin does not suspect that he has entered into a deadly battle with the killer, in which Agatha's life is at stake.