Comic and fantastic, gruesome and grotesque, Walpurgisnacht uses Prague as the setting for a clash between German officialdom immured in the ancient castle above the Moldau, and a Czech revolution seething in the city below. History, myth and political reality merge in an apocalyptic climax as the rebels, urged on by a drum covered in human skin, storm the castle to crown a poor violinist "Emperor of the World" in St. Vitus' Cathedral.