KGB officer Viktor Shvets is sent to occupied Taganrog, where he must organize and lead intelligence and the underground. Shvets gets a job in the occupation authorities under the guise of a Volga German, Gustav Schwartz. Thanks to his actions, the underground movement grows to hundreds of people: they commit sabotage, distribute leaflets, save Soviet prisoners of war and prepare an armed uprising. The Gestapo tries with all its might to expose the participants, captures underground members and tortures them, but the resistance of the Taganrog residents only grows.