The Great Patriotic War. Soviet intelligence officers led by Sergei Skorin and Andrei Losev are trying to track down a well-trained sabotage group that is staging large-scale sabotage in the rear of the Red Army on the eve of the Battle of Kursk. Andrey and Sergey are brothers, but there has been a conflict between them for many years. Andrey does not trust Sergei, because he suspects that his brother has been turned upside down.

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.