In this routine possession potboiler, Peggie Castle plays a suburban housewife being slowly driven mad by the intrusive, restless spirit of her husband's first wife, whose soul has been tainted by her participation in a Satanic cult headed by high priest Father Renall (Otto Reichow). The woman's husband (Arthur Franz) and his sister (Marsha Hunt) decide to infiltrate the cult in order to put an end to its murderous practices, but it is only through the intervention of a former cultist (Marianne Stewart) that they are able to overthrow the evil master's reign of terror once and for all. The tepid screenplay by Catherine Turney is an adaptaion of her novel The Other One. ~ Cavett Binion, Rovi