Hammer mainstay Terence Fisher made three movies for the cheapjack Planet outfit of which this (from a sci-fi novel by John Lymington) was the last. It's mighty hot for winter on the small island of Fara where scientist Lee has rigged up a lab in the security of the White Swan hotel. He believes the heat's caused by energy starved aliens. Cushing, the local doctor, is frazzled to death. Dynamite proves ineffective against the invaders, but as all seems lost a saving thunderstorm breaks. Even less exciting than it sounds.