Every time that sinister Oriental megalomaniac Dr. Fu Manchu is ready to kill, sounds of strange drums can be heard coming from -- well, nowhere really. In 1939, Republic Pictures purchased the rights to the first six of British pulp fiction writer Sax Rohmer's popular "Fu Manchu" stories. The result became the studio's second longest action serial and one of its most enduringly popular. The head of a sinister conglomeration known as the Si-Fan, Dr. Fu Manchu (Henry Brandon) goes in search of the Sacred Scepter of Genghis Khan, with which he hopes to rule all the tribes of the Orient and evict the foreign infidels. Helping the good doctor is Fah-Lo-Suee (Gloria Franklin), his Eurasian daughter, and a seemingly unlimited supply of Dacoits, henchmen turned into slaves by having undergone frontal lobotomies. Dr. Fu Manchu is, as always, opposed by Sir Neyland Smith (William Royle) of the British Foreign Office. This time, however, Sir Neyland is not only aided by his very own "Dr. Watson," Dr. Petrie (Olaf Hytten), but also by a young American, Allan Parker (Robert Kellard), whose father (George Cleveland) had become yet another of Fu Manchu's many victims. Complicating the search is the attractive presence of Mary Randolph (Luana Walters) who, like most of her ilk, has a tendency to get herself into serious trouble at the most inopportune moments. Although the Oriental fiend appears all-powerful at times, Sir Neyland and his friends once again save the free world from enslavement -- although it takes them 15 chapters to do so.