After the suicide of the former head of the Einsatzgruppen SS Mankiewicz, Lieutenant Colonel Andrei Eliseev undertakes the search for war criminals from his group. Unraveling the chain of mysterious events of the past and present, Eliseev, together with the staff of the department, establishes that in August 1941, a detachment of Mankevich's punishers was located in the museum building, where a group of children from an orphanage was hiding, abandoned during the evacuation. After the neighborhood with Mankevich's squad, the children disappeared. With the help of Alex Lyutoy's secret archive, Eliseev finds out who was part of the squad. But all the surviving members of the squad die under mysterious circumstances.

The second season tells about the capture of another war criminal, the inhuman Dr. Herman Schultz, who conducted experiments in a concentration camp. Thirty years later, the KGB raises his case when an unknown maniac with a special handwriting brutally kills girls. Some of the clues point to Schultz, while the other part only confuses the investigation.

Mid-1970s. The special department of the Ministry of Internal Affairs receives information that the Nazi executioner-collaborator Alex Fierce did not actually die at the end of the war, but still lives in the USSR. He has the blood of more than 2,000 compatriots on his hands. The hunt begins for the cruel traitor, but he does not sit still either. The traces leading to his current identity are constantly being cut off, suspects are replacing each other, and the number of victims is growing.