 In the isolated Woodstock Farmer, the workaholic composer David Winter (Jon Finch) is depressed because he feels that his wife, the actress Mary (Prunella Gee), is unfaithful. In a stormy night, Lucinda Jessup (Patricia Quinn), a witch from the Seventeenth Century and former dweller of the farm, arrives in the barn and possesses David. Mary fights against Lucinda trying to recover David.