Yuri Bragin, after a year-long business trip, where he, as part of an investigation team, was investigating a high-profile case, returns to St. Petersburg. When he returns, he learns that the current head of the First Investigation Department of the First Directorate of the State Investigation Department, Vadim Maltsev, is retiring. With a high degree of probability, it is Bragin who will be offered his place. But Yuri is not a careerist and the position of the boss is not the goal of his life. A talented investigator likes to do "live work" more. And now he is again sent on a business trip. This time in one of the cities of the Leningrad region, where two girls were killed with a difference of a week. Here, in a small town, everyone knows each other, and this complicates the search for the criminal.

1927. Trans-Siberian Express. Secret documents that will determine the future of the USSR and China are being transported across Russia. Under the guise of ordinary passengers, foreign intelligence officers and real thugs are hiding, ready to do anything for the sake of documents. A young Red Army soldier and a former Tsarist agent have to team up to uncover a common enemy.

During the next duty, patrolman Vera Sedova single-handedly prevents a tragedy at the college, but a student dies in the process. She claims that the guy had a sawed-off gun, however, no weapons were found. The policewoman is cursed by her parents and the public. The only one who becomes humanly sorry for Vera is the appointed lawyer Ilya Nesterov. Ilya is more and more immersed in the case and is convinced that his client may be right.

After the death of the mother of twelve Kohl sent to an orphanage. Valentine is taking him from there. This lonely old woman is his dear aunt, with whom he had never been acquainted. Kohl is waiting for his older brother to come after him after his release from prison, and they will return home together.