And why for some the most innocent everyday things, like picking mushrooms or visiting the theater, turn into mysterious incidents? Katya always gets into all sorts of adventures, so she’s not too surprised when a police major comes to her and persistently asks about contacts with a complete stranger. One of the members of the group involved in the resale of tickets to the Mariinsky Theater to foreigners was killed, and a notebook was found in the pocket of the murdered man, in which the smallest details of Katya’s life were written. Yes, she often goes to the ballet and sometimes even brings foreign colleagues with her, but how could she be of interest to the criminal gang and why was the one of its members who was assigned to watch her killed?