Young American scientist Stephen Reinhart visits the village of Arkham in rural England to see his fiancée Susan (Suzan Farmer) and to meet her parents, Nathum and Letitia Witley, at their isolated mansion.
Nathum (Boris Karloff) is an embittered old man in a wheelchair. Letitia (Freda Jackson) – a bedridden woman covered with a heavy black veil – pleads with Stephen to take Susan away.
Meanwhile, Witley and his manservant Merwyn (Terence de Marney) make one of their frequent and mysterious trips to an underground room from which an unearthly light glows.
Returning from his mysterious journey to the lower depths of the house, Witley visits Letitia and scoffs at her pleas to let the girl leave. The woman’s face is now revealed – ugly with hideously disfigured fungus-coloured skin.
Stephen visits the village hoping to learn from the local doctor (Patrick McGee) what is happening at the Witley mansion. He hears from other sources that Susan’s grandfather died in the doctor’s arms but that the body was never seen by anyone afterwards.
As he returns to the mansion, Stephen is attacked by a black-robed figure but escapes.
He is determined to get Susan away from the house, and as they leave, they are drawn to the greenhouse from which a strange light gleams from a mound of glittering crystals. Meanwhile, a storm has risen, and they run back to the house to discover Letitia’s room is empty.
Stephen ultimately confronts Mr Witley and learns that a green meteorite had crashed nearby many years before and that the old man has been nurturing it in the basement, believing that it was enhancing their lives when its radiation has actually been grossly mutating all living things in the vicinity.
There is a happy ending for everyone except the monsters who die the ghastly deaths they deserve.
Adapted from a story by HP Lovecraft, the film was released in the UK as Monster of Terror on a double-bill with The Haunted Palace, starring Vincent Price and Lon Chaney. American International Pictures distributed the film in the US as Die, Monster, Die! on a double bill with the Italian sci-fi film Planet of the Vampires (1965).
Terence de Marney