A skeptical college professor discovers that his wife has been practicing magic for years.

Tansy Taylor, the wife of an English university professor, secretly practices witchcraft to further her husband, Norman's, career. When he accidentally discovers her secret, he destroys her instruments of black magic. Following Tansy's warning that his action has left him vulnerable to evil forces, Norman's luck changes: a girl student charges him with rape, her boyfriend threatens him, and his car runs into a ditch. Then, one evening, Tansy disappears; Norman finds her nearly dead in a graveyard. When he brings her home, she attempts to kill him and later turns on the wife of one of his colleagues. Eventually, Norman learns that Flora Carr, the crippled wife of his rival for the chairmanship of the sociology department, is also a practitioner of witchcraft and has hypnotized Tansy into obeying her commands. That night, the Taylor home catches fire, and a huge stone eagle from one of the university buildings suddenly comes to life and attacks Norman. Later, the masonry supporting the eagle collapses, and Flora is killed as the stone edifice crashes to the earth.