A young coed (Nan Barlow) uses her winter vacation to research a paper on witchcraft in New England. Her professor recommends that she spend her time in a small village called Whitewood. He originally cam from that village so he also recommends she stay at the “Raven’s Inn,” run by a Mrs. Newlis. She gets to the village and notices some weird happenings, but things begin to happen in earnest when she finds herself “marked” for sacrifice by the undead coven of witches. It seems that the innkeeper is actually the undead spirit of Elizabeth Selwyn, and the “guests” at the inn are the other witches who have come to celebrate the sacrifice on Candalmas Eve. As one of them said when Nan walked away, “HE will be PLEASED.”

After a mysterious explosion leaves a large fissure in the ground, two young boys are confronted by an unknown phenomenon that inflicts severe radiation burns on one of them. There follows a spate of attacks at radiation establishments as the inexplicable life-form plunders radium stores. Dr Royston, an expert in atomic research, is brought in to explain and curtail the activities of this alien creature before it causes disaster.