SYNOPSIS

Joe, a writer recovering from a nervous breakdown, rents a cottage with his wife, Mary, in a small, peaceful village. The couple becomes acquainted with Shandra, a student of the occult, when Joe's car accidentally collides with the woman's bicycle. Soon, Shandra has introduced Joe to the occult, loaning him an ancient book on the subject. Mary, perceiving the insidious influence that the volume has on Joe, returns it to Shandra. She witnesses a strange rite that sends her, hysterical, back to Joe. At a party given by Shandra to celebrate the "Black Sabbath," Joe and Mary are drugged, and Mary becomes the "Devil's bride." Joe, helplessly watching, suffers another nervous collapse; in the hospital he becomes convinced that the entire incident was the invention of a troubled mind. Mary and Shandra (who Joe believes is his psychiatrist) arrive to take him to a homecoming party on the Sabbath...