Plot synopsis: In the summer of 1943, the Soviet leadership became aware of the achievements of German physicists in creating the atomic bomb. The task of obtaining secret information about the creation of a new type of weapon that can change the course of the war is given to a Soviet agent acting undercover, Frans Hartmann. A complex multi-way operation begins. Hartman involves the chief of German intelligence, Walter Schellenberg, in whose field of vision is the German scientific genius Werner Heisenberg. The Gestapo also steps in and assigns an "employee of the German Foreign Ministry" Dori to Hartman. At the same time, in Moscow, under the leadership of the talented physicist Igor Kurchatov, work on the Soviet atomic project was intensifying.