Alexander and Emily are in Germany for skiing. They take a side trip to Munich to visit their cousin Otto, who is a friend of Franz. Franz is the son of the famous composer Richard Strauss, who composed a new symphony especially for a music festival. Otto always plays through Strauss's compositions beforehand with his mouse orchestra, and in the process the mice notice that the notes have been switched by Strauss's assistant, Herr Räuber, so that he can take credit and Strauss is disgraced.