In a small Japanese town, Ko-Ko is appointed to the unenviable position of executioner. Knowing he must successfully perform before the appearance of the Mikado in a month's time, Ko-Ko finds a suitable victim in Nanki-Poo, who is distraught over his unrequited love for the maiden Yum-Yum. Nanki-Poo agrees to sacrifice his life if he is allowed to spend his remaining days with Yum-Yum, who is betrothed to Ko-Ko.
Carla de Hulvea is a rumba dancer who makes news by posing as a South-American heiress. She is doing fine with her hoax until she meets American Peter Jackson, a high-pressure promoter who is looking for movie-producing money. He does some big-time bluffing on his own in order to get Carla to invest in a film he is making with his partner, Roy Harley. Through Carla, Roy meets actress Diana West, who is given a role in the movie, and Roy falls in love with her.