Michael Whalen
— Robert Norton
Anne Nagel
— Nancy Fielding
William Bakewell
— Tom Fielding
Constance Worth
— Linda Pavlo
Hans Heinrich von Twardowski
— Capt. Gemmler
Jack Mulhall
— Chief Agent James Curtis
George Pembroke
— Prof. Karl Schmidt
Kenneth Harlan
— Agent Brown
Robert Frazer
— John Oliver
Hans von Morhart
— Heinrich
Michael Vallon
— Argus
Willy Castello
— Otto
C. Montague Shaw
— Franklin Prescott (uncredited)
Poppy Wilde
— Restaurant Patron (uncredited)