David Collins and Amy Jennings, two charming, innocent children are suddenly turned into demons. At first their pranks only annoy Maggie Evans, their governess. But soon she realizes they have become malicious, bent on destroying all at Collinwood. Convinced the children are possessed by a mysterious, supernatural power, and frightened for her life, Maggie turns for help to Barnabas Collins. Will his powers be strong enough to overcome the evil forces that captured the minds of the children before they - and Barnabas - are completely at the mercy of the Devil himself?