The plot takes place in 1942-1943, during the defense of Stalingrad. The Jew Viktor Strum is a talented nuclear physicist working in one of the country's institutes on the creation of an atomic bomb. At this time, Strum's relatives die in Nazi camps and NKVD dungeons, and persecution begins against him. The inventor can only be saved by his scientific brainchild, which Stalin himself became interested in. The state needs such a powerful weapon as an atomic bomb. The scientist has to make a choice: to remain faithful to science and work for the "leader of the nation" or to abandon his vocation and be destroyed.