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
Dr. Alexander Thorkel
Thomas Coley
Bill Stockton
Janice Logan
Dr. Mary Robinson
Charles Halton
Dr. Rupert Bulfinch
Victor Kilian
Steve Baker
Frank Yaconelli
Pedro
Paul Fix
Dr. Mendoza
Frank Reicher
Prof. Kendall
