Winter of 1942. The army group under the command of General Khudoyarov was ambushed. NKVD major Urusov goes there to track down the spy and saboteur. He takes three scouts with him and arrives at the headquarters under the name of Staff Colonel Yampolsky.
In the hospital, Urusov meets Natalia - the woman he loved and lost twenty years ago. He does not admit that he recognized her because he is conducting an undercover investigation. A saboteur blows up a hospital to destroy an unfortunate witness.
Colonel Velyaminov begins to suspect that Yampolsky is not who he claims to be. Perhaps he is a real saboteur. And Yampolsky-Urusov sends his scouts to the forest, to the commander of partisans who is the only person who can shed light on the past of the local special officer Kardash.
Scouts are sent to another partisan detachment where they see that the camp is empty, all are killed. In the distance, there is a knock of axes: saboteurs pretending to be partisans are chopping wood to put log on the road for German tanks which will soon arrive by train.