Robert Foxworth and Talia Shire star as a doctor and his wife who travel to Maine to research the impact of the lumber industry on the local environment. They begin to investigate a succession of mysterious and terrifying events: ecological freaks of nature and a series of bizarre and grisly human deaths. Something unimaginably horrible waits in the woods. Something unwittingly created by man, that will become an uncontrollable, merciless machine of destruction.