Anna Vlasova, the daughter of a well-known businessman, fell from the roof of a shopping center. Investigator Borisov finds no motive for the murder, especially since drugs were found in the girl's blood. But the sister of the deceased, Kira, does not believe that Anna decided to take her own life. She decides to look into the strange death of her sister and convinces Borisov not to close the case. He continues to look for evidence, and meanwhile, Kira herself is looking for the smallest thread ...