A series of murders of lonely old people took place in a provincial town. Another old woman died, allegedly from a heart attack. Her grandson, who has become the main suspect for the police, hires private detective Tatyana Ivanova so that she can figure out the death of Baba Varya and remove the absurd suspicions from him. Everything in this case indicated that death occurred naturally, without outside intervention. If only... it weren’t for a small clue: the keys to the front door, missing from her grandmother’s keychain... Tanya understands that everything is not so simple. After interviewing the neighbors, she finds out that that evening, shortly before her death, a young woman visited the old woman...