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.

• Hammer Film Productions
• Dean Jagger
• Leo McKern
• William Lucas
• Edward Chapman
• John Harvey
• Michael Ripper
• Anthony Newley
• Ian MacNaughton