Die Amadeus-Bande

There is a great hustle and bustle at the Castle of Treuenfels : A museum is soon to be opened on the castle premises - with original manuscripts by Mozart, Brahms and Mahler ! The Amadeus gang, too, have their hands full rehearsing for the big opening concert and surviving all exams unscathed. Even Igel works flat out to show his teachers what he can do. But then the Amadeus gang find out by chance that manuscripts from the collection of the new museum shall be sold off at an auction house.
How can that be ? Amadeus, Fliege, Niko, Cosi and Malu soon are certain that they have to be fakes !