In the first musical of the Monster High we will see them going to the magnificent city of Buu York, where one of them has been invited to a very special party. The guest is Cleo, but she takes her friends with her.
The party has to do with the return of a magic comet. In the city celebrates this return by all the height, but they do not know that they will have problems with this comet very soon.
The cause of the problems is Nefera, the sister of Cleo. Nefera does not seem to be very good and therefore uses her powers to do with the comet what she wants. She has terrible plans, so if you do not stop her, you do not know what she can do with the comet.
The Monster will have to put aside the parties to try to stop in time Nefera, who is determined to commit madness.