During the Cold War, U.S. bomber jets are equipped with fail-safe boxes that instruct pilots when and if to attack. When an attack order is inadvertently administered due to a system malfunction, the President of the United States (Henry Fonda) must scramble to fix the mistake before the bombs are dropped on Moscow. He manages to stop almost all the bombers headed for Moscow, except for one determined pilot who manages to complete his mission, with deadly consequences.