After the disappearance of his brother, antique dealer Robert Manning (Mark Eden) travels to the remote country manor of Greymarsh where he was last seen. There he stays with the charming J. D. Morley(Christopher Lee) and his beautiful niece, Eve (Virginia Wetherell). However, the Morley family are descendants of Lavinia Morley (Barbara Steele), the legendary Black Witch of Greymarsh. As Robert continues to investigate the disappearance of his brother, he is haunted by horrible dreams about black masses and ritual sacrifices. Robert ends up seeking the wheelchair bound Professor John Marshe (Boris Karloff), an expert on the occult, for help.