Night of the Big Heat is a science fiction novel written in 1959 by John Lymington. It tells the story of an unnamed British island that is experiencing a bizarre and stifling heatwave.
The main characters are a former novelist named Richard Callum and his wife Frankie, who own a pub called the White Lion. Richard has hired a secretary to help out on his new book, Patricia Wells, who turns out to have an obsession for Callum. A visiting scientist named Harsen reveals, ultimately, that the reason for the extreme heat is that an alien race of spiders are "beaming in" scouts from their home planet via an improbable "radio wave" ray which generates intense amounts of heat as a side effect.
The spiders themselves are carnivorous and eat humans, and give off bodily heat intense enough to burn alive any person who gets too close to them. Together with Harsen, Patricia, and science fiction author Vernon Stone, the Callums try to make it to the island's radio station to call for help so that they can thwart the invasion.
The novel was adapted into a 1967 film, Night of the Big Heat (also known as Island of the Burning Doomed) by Planet Film Productions.