Cast
Lorne Brass
Klaus Fuchs
Lia Sargent
Mrs. Wisnovsky
Michael Tucker
Leo Szilard
Hume Cronyn
James F. Byrnes
John Seitz
Ralph A. Bard
Romano Orzari
Leo Szilard's Prime Scientist (uncredited)
Anne Twomey
Kitty Oppenheimer
Lawrence Dane
Ken Pogue
Dwight D. Eisenhower
Tony Shalhoub
Enrico Fermi
Isabelle Mejias
Mrs. Trowbridge
Scott Thomson
Chemist
David Strathairn
J. Robert Oppenheimer
Michael Sinelnikoff
Lord Rutherford
Bernie McInerney
Jonathan Wise
Robert Serber
Michael J. Reynolds
Kenneth Bainbridge
Olek Krupa
Edward Teller
Patrick Breen
Richard Feynman
Roland Hewgill
Army General
David Ogden Stiers
Franklin D. Roosevelt
Tom Butler
Captain DeSilva
Harry Standjofski
Robert Wilson
Brian Dennehy
Gen. Leslie Groves
Ron Frazier
Colonel Pash
Gary Reineke
Groves's Commanding Officer
Alan Scarfe
Heinar Piller
Fleischmann
Timothy Webber
Colonel Lansdale
David Gow
Jack Wisnovsky
Dee McCafferty
William 'Deke' Parsons
Hal Holbrook
Gen. George Marshall
John McMartin
Dr. Arthur Compton
Vlasta Vrana
Hans Bethe
Barnard Hughes
Henry Stimson
George R. Robertson
Ed Condon
David Ferry
Army Major
Arthur Holden
Scientist (uncredited)
Ron White
Colonel Nichols
Richard Dysart
President Harry S. Truman