All Cast
Richard O'Sullivan
Roger Court
Alida Valli
Roberta Gleukovitch
Eduardo Ciannelli
Dr. Vivaldi
Trevor Howard
Major Roger Court
Richard Basehart
Joe Hamstringer
Stephen Murray
British Consul in Venice
Arnoldo Foà
Commissioner
Guido Celano
Chief Constable
Helen Goss
Undetermined Role
Giorgio Costantini
Pescovitch
Angelo Cecchelin
Luza
Nino Vechina
First Killer
Armando Papette
Second Killer
Giovanni Karuz
Third Killer
Joan Butterfield
Mrs. Harrington
Alessandro Paulon
Morgan
Remington Olmsted
Ramondo