Supercriminal Fu Manchu plots to freeze the world's oceans with a diabolical new device. With his evil daughter, Lin Tang, his army of Dacoitys, and the help of the local crime organization led by Omar Pasha (whom Fu Manchu double-crosses), Fu Manchu takes over the governor's castle in Istanbul which has a massive opium reserve, to control the largest opium port in Anatolia, a fuel for his machine. Fu Manchu needs the help of an intelligent scientist with an ailing heart whom he has imprisoned. In order to keep the scientist alive he kidnaps a doctor and his wife to give the scientist a heart transplant from one of his obedient servants. Opposing him from Britain's Interpol are his nemeses Nayland Smith and Dr. Petrie.