Having become an unwitting witness to the robbery of a cafe, Seleznev intervenes and kills two attackers, saving the life of a boy who happened to be on the scene. Soon, Irina Molchanova, the mother of drug addict Tamara, who died many years ago as a result of a special operation conducted by Seleznev, comes to him. Feeling remorse, he undertakes to find ... the grandson of Molchanova, whom Tamara gave birth to shortly before her death.

The mysterious disappearance of seventeen-year-old Sonya Pankova and her thirteen-year-old admirer Vasya Afanasyev during a school trip to the museum forces investigators to start looking for a motive for what happened. Soon they manage to hot on the trail to find Afanasyev, who decided to stage his abduction and was caught together with his accomplice while transferring the ransom by his father.