In a mythical Japan, Ko-Ko, a cheap tailor, has been appointed Lord High Executioner and must find someone to execute before the arrival of the ruling Mikado. He lights upon Nanki-Poo, a strolling minstrel who loves the beautiful Yum-Yum. But Yum-Yum is also loved by Ko-Ko, and Nanki-Poo, seeing no hope for his love, considers suicide. Ko-Ko offers to solve both their problems by executing Nanki-Poo, and an agreement is reached whereby Ko-Ko will allow Nanki-Poo to marry Yum-Yum for one month, at the end of which Nanki-Poo will be executed, in time for the arrival of the Mikado. But what Ko-Ko doesn't know is that Nanki-Poo is the son of the Mikado and has run away to avoid a betrothal to an old harridan named Katisha. The arrival of the Mikado brings all the threads of the tale together.