Jeffrey Hunter
— Captain Bill Ranson
Annemarie Düringer
— Rolande Hertog
Nigel Patrick
— Major Julien Howard
David Kossoff
— Dr. Mulder
Rolf Lefebvre
— Hans Faber, chief spy
Larry Burns
— Martins, building porter-spy
Anthony Ostrer
Claude Kingston
— Willem Mulder
Robert Raglan
— Lt. Miller
Peter Prouse
— Sgt. Bill Parrish
Philip Bond
— Piet van Wijt
Otto Diamant
— Mr. Hendrijk
Marianne Walla
— Mrs. Hendrijk
Beth Rogan
— Mary Ann Lennig
Arthur Gross
— Jan Guldt
Wolf Frees
— Brauner, shot spy