"Four explorers are summoned to Peru by the brilliant physicist Dr Thorkel. They discover a rich source of radium and a half-mad Thorkel who shrinks them down to one-fifth their normal size when they threaten to stop his unorthodox experimentation."
Albert Dekker
as Dr. Alexander Thorkel
Thomas Coley
as Bill Stockton
Janice Logan
as Dr. Mary Robinson
Charles Halton
as Dr. Rupert Bulfinch
Victor Kilian
as Steve Baker
Frank Yaconelli
as Pedro
Paul Fix
as Dr. Mendoza
Frank Reicher
as Prof. Kendall
Jane Webb
as Woman
Billy Wilkerson
as Silent Indian
Dale Van Every
Producer
Tom Kilpatrick
Screenplay
Ellsworth Hoagland
Editor
Merian C. Cooper
Gerard Carbonara
Original Music Composer
Malcolm Stuart Boylan
Ernest B. Schoedsack
Director
Henry Sharp
Director of Photography
A. E. Freudeman
Set Designer
Richard Olson
Sound Recordist
Hollingsworth Morse
Assistant Director
William LeBaron
Executive Producer
Hans Dreier
Art Direction
Robert Odell
Harry Lindgren
Charles Gemora
Makeup Artist
A. Earl Hedrick
Albert Hay Malotte
Ernst Toch