A young museum curator Isabelle (Katie Goldfinch) is sent to look at an ancient artefact, discovered in the basement of a stately home in Shropshire. Welcomed into the sprawling manor house by a seemingly hospitable family; Karl (Larry Rew), his wife Evelyn (Babette Barat) and their beautiful daughter Scarlet (Florence Cady), but all is not what it seems, as a dark and terrifying secret hangs over them.

Army radiation experiments awaken a subterranean monster from a fissure that feeds on energy and proceeds to terrorise a remote Scottish village. An American research scientist at a nearby nuclear plant joins with a British investigator to discover why the victims were radioactively burned and why, shortly thereafter, a series of radiation-related incidents are occurring in an ever-growing straight line away from the fissure.