While visiting a restaurant near Monte Carlo Nyland Smith and superintendent Weymouth are informed that Dr. Petrie who had been stricken by a mysterious disease has just died, and Smith hurrying to the hospital to investigate Petrie's reported death is overcome by an emulser gas. he regains consciousness in Dr. Fu Manchus subterranean laboratory where he finds Paul Sterling the young botanist, an assistant of Petrie's, who had disappeared from the Villa Jasmine earlier. After Dr. Fu Manchu conducts them through a scientific research room he places them in luxurious appointed apartments there to await a further summons. Smith and Sterling decide to make a break for freedom but suddenly the door opens and Fa Lo Swee stands before them...