Christopher Lee stars as the eponymous Chinese criminal mastermind in this adaptation of the Sax Rohmer novel. Having watched his execution, Detective Nayland Smith (Nigel Green) can be forgiven for thinking that the evil of Fu Manchu is finally at rest, but when a mysterious deadly gas is tested on a sleepy English town, the trail of clues lead to an impossible conclusion - that Fu Manchu is alive and well, and planning yet more criminal outrages. It becomes a race against time to stop the evil genius from testing his deadly gas on the whole of London, his first step in an attempt to take over the world.