Dr. Fu Manchu is on the run but still up to his nefarious schemes. He captures Dr. Petrie’s daughter Fleurette and takes her to London where Alan Sterling, her fiancé, and Nayland Smith track him down. Fu Manchu is cut off from his Si-Fan resources so he comes up with a quick money making plot; turning lead into gold. Burmese stranglers, British seamen, abandoned mansions, a roaring furnace, explosives, and an underground lair all play a part.