This docudrama chronicles 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 narrative is delivered by Robert Oppenheimer (Hume Cronyn) and Major General Leslie Groves (Brian Donlevy), starting with the Nazis' stated goal of developing an atomic bomb. The United States, along with Britain and Canada, responds by launching its own atomic program. The film presents significant milestones: Fermi's successful atomic chain reaction; construction of the Oak Ridge complex in Tennessee; production of the first batch of plutonium; testing in the Nevada desert; and finally, the dropping of the atomic bomb on Hiroshima. Cast: - Brian Donlevy as Major General Leslie R. Groves - Robert Walker as Colonel Jeff Nixon - Tom Drake as Matt Cochran - Beverly Tyler as Anne Cochran - Audrey Totter as Jean O'Leary - Hume Cronyn as Dr. J. Robert Oppenheimer - Hurd Hatfield as Dr. John Wyatt - Joseph Calleia as Dr. Enrico Fermi - Godfrey Tearle as President Franklin D. Roosevelt - Victor Francen as Dr. Marre - Richard Haydn as Dr. Chisholm - Jonathan Hale as Dr. Vannevar Bush - John Litel as K. T. Keller - Henry O'Neill as General Thomas F. Farrell - Warner Anderson as Captain William S. Parsons - Barry Nelson as Colonel Paul Tibbets, Jr., pilot of the Enola Gay - Art Baker as President Harry S. Truman - Ludwig Stössel as Dr. Albert Einstein Runtime: 112 minutes.