This ranks as one of the most gripping and suspenseful movies ever produced in U.K.. Richard Todd and Anne Baxter give off superb display of acting, maintaining the director's ultimate objective of keeping the suspense rolling without any clue or hint towards its final unravelling of the mystery. In fact, the famous Hollywood actor Douglas Fairbanks himself (Producer ?) implores the audience, at the end of the movie, not to reveal the ending to others who are yet to see the movie. The play of shadow and light, especially on Richard Todd's face, adds to the foreboding and eerie feeling. This is one movie, where the producers' usual pronouncement of audience being forced to sit at the edge of seat really holds true. A movie that is surely a must for any serious moviegoer's collection.