Indeed he is and after the ultimate poison distilled from a rare flower found in Tibet. Professor Muller (Walter Rilla) has been working on the poison and he is captured by Fu Manchu. He is forced to complete his work on the poison after his daughter Maria (Karin Dor) is also captured and threatened by Fu Manchu with an awful death...
With the help of Muller's assistant Carl Jannsen (Joachim Fuchsberger) and Petrie (Howard Marion-Crawford) - though he seems more a hindrance than a help - Nayland Smith battles to stop Fu Manchu killing everyone in London...
It is all a load of tosh obviously but glorious tosh! Christopher Lee is terrific as Fu Manchu along with his merciless daughter Lin Tang (Tsai Chin). The film has plenty of action and also plenty of pseudo oriental nonsense. If you don't take it seriously then the film is great fun.
