Susan Foster (Carla Lehmann) is cast into a web of international intrigue when she decides to hide fugitive British agent Alan Thurston (James Mason) from suave Nazi Dr. Muller (Walter Rilla). Thurston's mission is to travel to the Vichy colony of Algiers and recover a camera revealing the exact location of Allied General Mark Clark and his colleagues who are soon to rehearse signals for the invasion of North Africa.