1943. Encircled near Smolensk, a German grouping unexpectedly broke through the ring and got out from under the blow. Soviet command is sure: the Germans had help from someone—someone who pointed out a weak spot in our defense. A detachment from the army counterintelligence S MERSH arrives to search for the enemy agent, under the command of Captain Alexey Sabl in. The operatives find out that during the occupation, an Abwehr intelligence school was actively operating in the area. Some of its graduates later infiltrated existing units of the Red Army. Sabl in learns the nickname of the German spy and identifies the circle of suspects. All that remains is to expose the traitor and take him alive…