In the middle of the night, an old woman with Alzheimer's disease enters someone else's apartment. She claims that this is her apartment and tells everyone about a certain Lyuba. Having found burn marks on her grandmother's body from cigarette butts and ropes with which she was tied, investigators believe that she was raped. However, this hypothesis is not confirmed. Bobrova and Pankratov establish the identity of the grandmother. This is Nina Glebova, who often visited the apartment as a child, where she was found. Nina's son Nikolai, who leads an asocial lifestyle, falls under suspicion. It turns out that he deliberately took the mother out of the nursing home in order to receive her increased pension. On the eve of Nina's discovery in the apartment, Nikolai's house was having a drinking binge. After interviewing the guests of the party, Bobrova and Pankratov go out to Nina's grandson Sasha and his friend Zhora, who works in the nursing home where Nina used to live.