Late 1940. Hitler''s armies are ravaging Europe. Ian Steele and Margaret Whitcombe of the British Secret Intelligence Service, meet in London, fall in love. They are soon separated. Margaret is assigned to SIS, Zurich, and Ian When Margaret, at SIS London, doesn''t hear from Ian, she, disguised as a nun, returns to Tours to look for him. She learns that French collaborators have put Ian in a Toulouse prison. She vows to free him.