The series is based on a true story of a Russian spy Colonel Isaev (Stirlitz) in Fascist Germany during 17 days in very end of WWII. Stirlitz has worked his way to the very top of the Fascist hierarchy without being caught. However, his "colleagues", top Hitler's officers Borman, Mueller, Schellenberg are beginning to suspect him. Stirlits is constantly walking on the edge between his two identities, sending information to Russia, while skillfully maintaining the appearance of loyalty to fascist regime.