A pretty good thriller with an engaging mystery at its core. Parts of it feel very Hitchcockian, particularly the scene with Van Johnson's character stumbling around the bomb-damaged building, which is truly heart-in-mouth stuff. The atmosphere is enhanced by the excellent location shots of fog-bound London, although some of the minor characters like the pub landlady are a bit clichéd. Overall, nothing ground-breaking or remarkable, but definitely worth a look.