During WW2, a French woman living in England volunteers to work for British Intelligence in Nazi-occupied France.
Trivia
Anna Neagle spent a year with Odette Hallowes visiting the various prisons and camps where she was held and being introduced to other surviving S.O.E. Agents. Odette said of her, "She was absolutely into it. In fact, it took one year after the end of the film to get back to normal. She was more upset by doing that film than I was reliving the experience."