Great excitement in the principality of Allegretto. Professor Sound, owner of a sanatorium for musical instruments, has succeeded in a sensational invention: the music pill. Once swallowed, it transforms the worst sourpuss into a cheerful singing and dancing contemporary. The success is striking, as is the echo in the international media. The pill produces satisfied tax officials, happy drivers, elated policemen and laughing burglars. Tourism flourishes, as a trip to Allegretto soon becomes more popular than a holiday in Hawaii. But dark clouds are gathering over the dwarf state when Field Marshal General Heinz mobilizes his troops in neighboring Moderato. Allegretto is to be stripped of its cheerfulness "in the name of the people".