Middle of the night in someone else's apartment gets old woman suffering from Alzheimer's disease. She claims that it was her apartment and tells all about a certain Luba. Finding the body burns grandmother of cigarette butts and ropes that bound her, investigators believe that she was raped. However, this hypothesis is not confirmed. Bobrov and Pankratov establish the identity of her grandmother. This is Nina Glebova, a child often visited the apartment where it was found. Suspicion falls Nina's son Nicholas, a leading asocial way of life. It turns out that he deliberately took his mother from a nursing home to receive her pension increased. On the eve of discovery by Nina in an apartment house in Nicholas held revelry. Interviewing party guests, Bobrov and Pankratov go to Nina's grandson Sasha and his friend Zhora working in a nursing home, where previously lived Nina.