The operational-search group of the Front's counterintelligence department, led by Captain Alekhin, is looking for a sabotage group code-named "Neman". The group of saboteurs is headed by the German agent Mishchenko, well known to Alekhin, whose task is to collect intelligence necessary for the German command to determine the direction of the main attack of the Soviet army. Alekhin and his group, in the course of a wide search, work out one version after another, but each time Mishchenko manages to get away.