At his uncle’s behest, the young Karl-Heinrich, Hereditary Prince of Saxe-Karlsburg, is sent to Heidelberg to study for a year. After a joyless youth in the gloomy, stately Karlsburg Castle, the prince embarks on the most carefree period of his life. He falls hopelessly in love with Käthi, the charming daughter of his landlords. But duty calls: the prince is gravely ill, and Karl-Heinrich must return to assume his duties as heir apparent and future ruler.

Erbprinz Karl-Heinrich
Doktor Jüttner
Käthi
Fürst von Sachsen-Karlsburg
Gastwirt Rüder
Kammerdiener Lutz
Diener Schölermann
Staatsminister Haugk
Kammerherr von Metzing
Graf Detlev von Asterberg
Kammerherr von Feldbach
Helene, Serviermädchen