High in the peak stands the Blue Moon Inn, the home of Matthew Hopkins for as long as anybody cares to remember. Here is the place where once every century the moon appears to turn blue and all-manner of strange and terrifying events are said to be unleashed upon the land. The time has come and with it a small group of interested individuals. An astronomer, an astrologer and a documentary filmmaker all arrive unaware of the evils that will befall them. A nightmare unfolds upon each one until the final shocking conclusion.