David Marshall Williams is sent to a prison farm where he works in the tool shop and eventually develops the precursor of the famous M-1 Carbine automatic rifle used in World War II.

James Stewart
as Marsh Williams

Jean Hagen
as Maggie Williams

Wendell Corey
as Capt. H.T. Peoples

Carl Benton Reid
as Claude Williams

Paul Stewart
as 'Dutch' Kruger

Otto Hulett
as Mobley

Rhys Williams
as Redwick Karson

Herbert Heyes
as Lionel Daniels

James Arness
as Leon Williams

Porter Hall
as Sam Markley