As the Prophet of Doom warns "The End is Near!" Judgment Day comes at last. Gabriel blows his trumpet with a showman's flair and the dead leap from their graves. However, in the scramble to dispose of the world's population in time, Death has missed one young man, Jonathan Zzoam. Satan gets Gabriel to agree, as a recompense, to allow Jonathan to rule the world for a day, after which he will be judged with all the rest. Of course Satan and his secretary Miss Demonia have ulterior motives - as everyone knows, "Power corrupts, and absolute power corrupts absolutely."
Many historical personages are present among the resurrected: Jonathan drafts Shakespeare to write a love song, puts Ceasar in charge of a parade, and has Marie Antoinette plan a dinner party. His best friend Finny falls in love with Joan of Arc. But Jonathan seems to forget the simpler side of life and his relationships with his girlfriend Elaine, his parents, and Finny gradually deteriorate as his plans become ever more grandiose. Soon he has alienated everyone and can only command affection. By the end of the act the only one happy is the Prophet of Doom, whose dreams are finally coming true.
As the act begins, gravediggers, morticians, and undertakers commiserate with Death about their unemployment. Meanwhile, the dinner party Jonathan ordered is getting under way. Chaos ensues as Henry VIII discovers that all of his wives are there and Oedipus finally gets his chance at Siegmund Freud. Jonathan enters, restores order with a heavy hand, and leaves. Mr. and Mrs. Zzoam are dismayed at his conduct, and Finny's parents don't like the fact that Joan is Catholic, so they commiserate in song.
Finny and Joan dance, then plan to sneak out separately while Jonathan isn't looking. Satan and Miss Demonia find Finny on the terrace and taunt him by revealing their plan - since Jonathan is corrupted, he will take everyone he commands down with him. In fact, jealous of any genuine affection, Jonathan has prevented Joan from leaving and forced her to dance with him. Finny arrives just as he forces a kiss.
In the mental anguish that follows, Jonathan allows everyone to disperse. Finny, Joan and the Dead flee ahead of him. Jonathan, wandering through the night alone, has a strange conversation with the Prophet of Doom and decides that the only way to salvage things is to give up his power to command. Satan is dismayed at first, but quickly realizes that this, too, is a form of vanity that can be exploited. And it alone is not sufficient to placate everyone Jonathan has hurt. The Dead become a lynch mob under the theory that Jonathan hasn't died yet and could possibly still be killed. As the clock strikes midnight, marking the end of Jonathan's day, everyone is at each other's throats and Satan and Miss Demonia appear to have won.
At the Judgment, Jonathan realizes his mistakes and takes responsibility for his actions and those of everyone he controlled. Gabriel reveals that he planned all these events as a way to foil Satan. The Judgment is indefinitely postponed and Death and the Prophet of Doom rejoice that they have their jobs back.