A happy Mrs. Grille, the music teacher of the Academy, returns with her choir from the international school festival for singing and music. They have won the first prize! And not only that, Mrs. Grille has also won something else: an admirer! This Austrian music professor is also promptly on the doorstep of the Academy the next day. He would like to invite Mrs. Grille and her choir to Vienna, and of course he will bear all the costs. But Sybille makes a strange discovery.