The year is 1943. Beria instructs his deputy Vsevolod Zamyatin to assemble a team of scientists to design the first Soviet atomic bomb. To do this in the midst of a war and in a short time is an almost impossible task. 

Under Kurchatov's leadership, secret Laboratory No. 2 begins work in Moscow, where the best minds from all over the Union become employees. Kurchatov convinces Zamyatin to include two scientists in the project: the audacious and self-confident Frolov, who had previously discovered spontaneous nuclear fission, and the radiochemist Karpova, who is in exile in Kazakhstan. And although Frolov and Karpova raise questions in the People's Commissariat of Internal Affairs, it was decided to fulfill Kurchatov's request. At the same time, Soviet intelligence is working to obtain the scientific information necessary for the project abroad. Agent Ekaterina Lazareva, a former physicist and Frolov's lover, manages to transfer the most important data about the Allied atomic project to the USSR. From now on, the Soviet Union needs to catch up with Britain and the United States in order to achieve nuclear equilibrium in the post-war world.