In ancient Japan, young Nanki-Poo, the son of the Mikado, runs away from home rather than marry the elderly woman his father has chosen for him. Disguised as a wandering minstrel, he arrives at Titipu and learns that his beloved Yum-Yum is to be wed to her guardian, Ko-Ko, the newly-appointed Lord High Executioner. When the Mikado decrees that an execution must take place within a month, Nanki-Poo agrees to be the victim if he will be permitted to marry Yum-Yum first and thus have one month of happiness before yielding Yum-Yum to Ko-Ko. Complications arise, however, because of a law stating that when a man is beheaded his wife must be buried with him. The dilemma is settled by forging a death certificate for Nanki-Poo and presenting it to the Mikado. Upon learning that the executed man was his only son, the Mikado demands that Nanki-Poo be brought back to life; Nanki-Poo stipulates that he will return to life only if he is permitted to have Yum-Yum for his wife. The Mikado consents and all ends happily, except for Ko-Ko, who is obliged to marry the mean-tempered woman intended for Nanki-Poo.