Dr. Ulrich zu Westerheimer is a German-born nuclear physicist working on the American atomic bomb project in Los Alamos. In 1943, he flies to Novosibirsk in Siberia for a meeting with his younger brother, Carl Friedrich, a fanatical Nazi who is also a nuclear physicist. Carl Friedrich was captured at Stalingrad and is to be flown to Hitler's headquarters in East Prussia with a Soviet peace proposal for Hitler. Hidden in the briefcase is a report by Nobel Prize winner Dr. James Chadwick regarding the infeasibility of a plutonium bomb. The report is genuine, but wrong. The Americans want to deceive Hitler with the report. But the NKGB (the Soviet Secret Police) play some deceptive tricks of their own.