When American student Stephen Reinhart (Nick Adams) arrives in the English village of Arkham to visit his fiancé Susan Witley (Suzan Farmer), he has no idea of the horrors awaiting within. Invited by Susan's mysteriously ill mother (Freda Jackson), Stephen is greeted acrimoniously by Susan’s father, Nahum (Boris Karloff), who makes it clear this visit is an unwelcome intrusion to the ornately furnished halls of the Witley estate, for Nahum is hiding a dangerous secret.

A meteorite has crash landed in the gardens, scorching the earth and emitting a mutating radiation that has transformed the greenhouse plants to pulsating giants, with horrifying and sickening side effects to the residents.

Based on H.P Lovecraft's story 'The Colour Out of Space', Die, Monster Die! is a British horror contaminated with mystery, shock and gore.