The action is too fast for anyone to be able to follow, and it constantly gets confused on the way, which doesn't improve the impression. The acting is good although grossly exaggerated all the way, and nothing here is really believable - it is more like some kind of a prehistoric James Bond sketch touching on both the fantastic and science fiction and being anything but realistic. The scenery is fascinating though, some scenes are really intriguing in terrifying obliqueness, while sadly the film was made some years too late. It deals with Nazi fifth columnists in England that plot an invasion by Cornwall, using a mine for cover, while in 1945 they had already missed the train by some years. It's a kind of adventure story for youngsters, you almost feel some presence of Enid Blyton in the set-up, so it is anything but dead serious. However, the corpses keep mounting, there is a momentous shoot-out, and you easily get lost in those caves. David Farrar was a dashing actor in the style of Douglas Fairbanks Sr, but he would make better roles than this rather amateurish imitation of Sherlock Holmes.