Docudrama on the development of the first atomic bomb. Told from the perspective of a film recovered from a time capsule several hundred years into the future, the story is narrated by Robert Oppenheimer (Hume Cronyn) and Major General Leslie Groves (Brian Donlevy) beginning with the Nazis stated goal of developing an atomic bomb. Along with Britain and Canada, the U.S. reacts by beginning its own atomic program. The major developments are all presented: Fermi's successful atomic chain reaction; building the huge complex at Oak Ridge, Tenn.; the production of the first supply of plutonium; the testing in the Nevada desert; and finally the dropping of the first atomic bomb on Hiroshima.