The Face of Fu Manchu

After the execution of Fu Manchu, a mysterious new criminal mastermind arises. Strangely, he acts the same as Fu Manchu. . .
Grisly strangulations in London alert Nayland Smith of Scotland Yard to the possibility that fiendish Fu Manchu may not after all be dead, even though Smith witnessed his execution. A killer spray made from Tibetan berries seems to be involved and clues keep leading back to the Thames.