Based on the novel of the same name by Tatyana Ustinova.

The unmarried Vladimir Arkhipov lived peacefully with his faithful mastiff and did not intend to make any changes in his life. Everything just happened. Lizaveta's eccentric neighbor died and left her an apartment and her so-called “orphan girl” as her inheritance.
However, the orphan turned out to be a grown-up girl named Masha, who caught the imagination of the lonely Arkhipov. But why didn't the neighbor leave her the apartment? Was it because the Path to Joy sect claimed it? Then Masha's half-brother from the provinces fell for her, and then they both disappeared. Concerned about their disappearance and thinking about the strange death of his neighbor, Arkhipov begins to investigate.