It is July 1941, and the Nazis are advancing towards Kiev at great speed. As the situation in the city becomes more tense and untenable, Ivan Rokotov's job, as senior investigator at the Kiev Military Prosecutor's Office, becomes increasingly busier. When Nikolay Mirsky, Deputy Chief Military Prosecutor of the Red Workers' and Peasants' Army, unexpectedly arrives from Moscow, he quickly decides to form a special squad at the Military Prosecutor's Office of the Front to include Rokotov and Svetlana Yelagina, a former investigator for the Dnepropetrovsk Crime Investigation Department. Rokotov and Yelagina are tasked with investigating major cases by acting both at the frontline in the territory of the Kiev Fortified Area, and in the city itself, where rising criminals are joining German subversives in infiltrating the city, while a number of Soviet government representatives are happily profiting from other people's misery and suffering. Rokotov, who was educated at a high school during the reign of the last Russian Tsar, and Yelagina, an ardent Young Communist League member, have to overcome their political and ideological differences before being able to work together, reacting quickly and efficiently to the constant changes in the city. Fighting against both overt and clandestine enemies, Ivan and Svetlana begin to experience a shift in their professional relationship, which grows into real love, possible only in the face of certain death. Meanwhile, Mirsky is holding his own investigation aiming at exposing a spy organization that has been operating in Kiev since the late thirties, but his search leads him unexpectedly to a secret conspiratorial group directly connected to his and Rokotov's pasts..