In Moscow, under mysterious circumstances, a young policeman is killed. The witness of the murder is his girlfriend Lera Nemchinova. The case is transferred to Petrovka. Gordeev's bosses insist on considering the version of the possible connection of cadets with criminal structures. Kamenskaya simultaneously begins to develop her own version. The fact is that Lera is the daughter of a famous composer who died ten years ago. Nemchinov was shot at his own dacha, and his father, Grandpa Lera, confessed to the murder. After serving his sentence, Nemchinov the elder returned to Moscow and now lives with his granddaughter. Kamenskaya meets Lera. On the girl's hand, she sees a ring that took place in the case of the murder of a high-ranking official's wife. The murder, committed several years ago, was never solved, and no one else saw an expensive piece of jewelry.

In Moscow, a famous dentist was killed - Yakov Gorobetsky. The corpse is discovered by the son of the murdered man - Vitaly. The results of the work of experts lead to a consequence of an unexpected discovery. Vitaly is not Gorobetsky's own son. His real father - Bakhtemyev - led a major criminal group in St. Petersburg, he was arrested and shot in the early eighties. Mother Vitaly married Gorobetsky, who adopted the boy. During the investigation, Kamenskaya finds out that the mother of Bakhtemyev the elder has been killed in Petersburg. The alleged killer was detained, but he managed to escape. Kamenskaya is going to Petersburg.

1998 year. Gordeev happens to be a witness of a crime - a girl is killed. He detains the killer. This maniac, on account of which more than a dozen such crimes. All the victims are female students, on the corpses the murderer leaves greeting cards. The medical examination finds him insane and sends him to compulsory treatment. Our days. At the institute, where Gordeev's daughter is studying, there is a murder. On the corpse of the student, they find a greeting card. The investigation manages to find out that two weeks ago a maniac managed to escape from a psychiatric hospital, and the victim was not an accidental victim, it was her father who was an investigator in the case of a maniac. The search for a maniac does not yield any results. In the meantime, the son of another participant in that trial is being killed. There are no such coincidences. Gordeyev understands that the next victim may be his own daughter. Together with Kamenskaya, they must reach the track of a maniac before he gets to Lena Gordeeva.

As part of the exchange of experience with foreign colleagues, Gordeev and Kamenskaya go to Finland. In the hotel where they live, there is a murder. The victim is a young Russian actress. Kamenskaya participates in the investigation. In the circle of suspects are all the members of the crew. Each of them had reasons to settle accounts with the victim. However, during the investigation it turns out that in the childhood with the actress something terrible happened. And only after figuring out the case a decade ago, Kamenskaya will be able to calculate the killer.

The wife of a large restaurateur Safronov - Elena is killed. Safronov insists on doing this business on Petrovka. From the very beginning, Kamenskaya suspects the businessman in the murder of his wife. However, it soon becomes clear that Lena had a lover. But Nastya can not meet with him. Upon learning of Elena's death, Vasili committed suicide. In his suicide note in the murder of a loved one, he accuses Safronov. Dotsenko detains an assistant restaurateur, but then the FSB officers interfere in the matter.

After an unsuccessful fall, Kamenskaya breaks her leg and finds herself in the hospital. After two months, the improvement does not come. Tomilina recommends that she turn to the psychologist Anichkova, perhaps she will be able to help. Nastya does not have time to contact the doctor, Anichkov is killed. The investigation of this crime is charged by Dotsenko. Misha offers Kamenskaya to stay at his dacha, fresh air will probably speed up recovery. The first night in the country house Kamenskaya sees a man who is watching the site. Dotsenko meets with patients Anichkova. She advised employees of the company "Planet". The nephew of the murdered Gennady tells that shortly before the murder, he witnessed a scandal between Anichkova and one of her clients, but he did not see the woman's face. Dotsenko takes the victim's relative to the corporate event of the "Planet", Gennady should try to calculate the lady by voice. During the event, a single witness is also killed. A certain person continues to follow Dotsenko's dacha. Kamenskaya is frightened. Together with Tomilina, they decide to find a mysterious patient on their own.