This British B-film crime-quickie has elements of both horror and sci-fi. Hanley is an effervescent young reporter who tackles the story of a mysterious, hooded black rider who is seen (on a motorcycle no less) near a crumbling castle on full moon nights. Who is the rider and what is his strange purpose? After much sleuthing, it soon becomes evident that England is faced with a plot so sinister, that the atomic destruction of it's cities may result if it the threat isn't thwarted in time.