Mara (Lila Zaborin) a "black" witch, practitioner of the occult, black magic and evil incarnate, is the leader of a coven of voluptuous, scantily clad beautiful young women who vent their sadistic love for passion and pain on helpless victims as they perform the body ritual of a hideously, macabre dance of death, carrying aloft flaming torches and plunging spears into their human male sacrifices in a gory ceremony to titillate their pulsating pleasures and sanctify the evil desires of this Queen of the Witches.
Mara is approached by Rodannus (Ray Myles) enemy agent of a foreign power, accompanied by his henchman, Barth (Paul Wilmoth) with the request that an Ambassador representative to the United Nations from another country be eliminated by means of her magic powers. During this meeting, Rodannus demands proof of her mystical power and she causes a wine glass to shatter in his hands. When the enemy agent leaves, Mara keeps the bloodied handkerchief he had used on his cut hand.
Lorraine (Leslie McRae) a newcomer to Mara's coven, persuades her boyfriend, Mark (Tom Pace) an unbeliever, to attend a séance. Astounded by the results, during which Mara has conjured up two spirit guides and a ghost, and worried about Lorraine's involvement, Mark decides to consult Dr. Helford (Victor Izay) a "white" witch or warlock, and an expert on psychic phenomena. After Mara has caused the Ambassador's death at a party, Rodannus fears that she may turn her powers against him, and sends Barth to kill both Mara and her high priest Toruke (William Bagdad). Barth also kills a young girl, Roberta (Linn Henson) but she manages to scratch his face before she dies. Meanwhile, Dr. Helsford agrees to help Mark. By means of witchcraft, Mara has caused Barth to kill a cat instead. She now restores Toruke to like and using Rodannus' bloodied handkerchief and Barth's scratched skin from the fingernail parings of the dead girl, Mara eliminates both Barth and Rodannus in a macabre and bloody manner.
Mark and Lorraine are to attend another séance at Mara's residence and they discuss with Dr. Helsford the possibilities of age regression under hypnosis which Mark is to undergo. The doctor warns them of the dangers of dabbling in the black arts. He psychometrizes an amulet Lorraine is wearing which Mara had given her as protection against unfriendly demons. After the pair leave for the meeting, the disturbed Dr. Helsford, sensing an evil aftermath, enlists the aid of three other scientists interested in psychic phenomena and they decide to visit Mara's home where the meeting is to be held. During regression, Mark is shown to have been killed by Indians in a previous life as a frontiersman and now, drugged by Mara, he is to be offered up as a human sacrifice in an effort to conjure up Lucifer, the Devil himself. Mara and her coven of witches are soon terrified as an unseen presence takes over. The building rumbles and trembles as utter chaos reigns. The unseen terror possesses the bodies of the young witches who turn against Toruke and kill him, and they then turn against each other. Outside, Dr. Helsford fights the evil within by means of exorcism and manages to restore order and sanity, driving the evil unseen presence away. When the quartet of scientists enter the building, all is death, and destruction. Mark, Lorraine and all the others are dead. Only a bat clings to the ceiling and dislodging it, Dr. Helford, knowing its true identity, kills it and throws it on some burning coals. At last, Mara pays for the consequences of evil, as her translucent, vaporous form floats upwards in a raging, screaming death.
