Sixteen-year-old schoolgirl Masha Kolobova was found dead on the street. The forensic medical examination establishes that shortly before her death, the deceased had sexual contact. The keys to the unknown premises were found with the girl. The mother of the murdered woman claims that her daughter was an exemplary student and studied in a theater studio. The head of the studio, Stanislav, who had previously been seen in dubious ties with his students, falls under suspicion.