Rat' mal, wer heut bei uns schläft...? (1969)

At the Glücksburg estate, a spring whose aphrodisiac effects made the estate notorious rises from the ground. After the Baroness leaves the estate, sisters Jennifer and Veronika lead a dissolute life, despite the watchful eye of their strict chaperone, Sybille, including with their violin teacher, Philoni. One day, the third sister, Alexandra, arrives at Glücksburg from boarding school together with Frank, an art student. However, the newcomers seem more interested in playing chess, so attempts to pair Alexandra with the forester and later with Robert, at Jennifer’s engagement party to Robert, come to nothing. Then Baroness Henriette arrives and announces that she will soon marry the Conte di Casagrande. At last, Alexandra and Frank find their way to each other, while the unfaithful Conte takes an interest in the maid, Frosine. The chaperone, the violin teacher, and the forester are dismissed, while the Baroness finds happiness with the butler. He is also the one who knows the secret of the miraculous spring and monitors its dosage.