The Emperor of Japan, the Mikado, wants an execution, and Ko-Ko, the Lord High Executioner, is desperate for a victim. He agrees that his fiancee Yum-Yum can marry her true love, Nanki-Poo - but only for a month. In return, Nanki-Poo agrees to be executed, leaving Ko-Ko to reclaim Yum-Yum. When legal complications arise, Ko-Ko is forced to pretend that the execution has taken place. But Nanki-Poo turns out to be the Mikado's runaway son, and to save his neck, Ko-Ko finds himself blackmailed into marrying Nanki-Poo's own fiancee Katisha... allowing Nanki-Poo to marry Yum-Yum.