Rachel and the Many-Splendored Dreamland (3) (Books of Unexpected Enlightenment)

It’s Halloween at the Roanoke Academy for the Sorcerous Arts, and Rachel Griffin is stirring up the dead!
 
All her life, Rachel has wanted to visit Beaumont Castle in the kingdom of Transylvania, the last known location of her hero, librarian-adventurer “Daring” Northwest. Only falling out of the land of dreams onto her face was not how she had expected to arrive.
 
Now, the castle is right there, looming over her. Only her best friend, the Princess of Magical Australia does not want to go in, so as to avoid an international incident. But what if the castle holds some clue as to her hero’s final fate?
 
And who was that mysterious figure hanging by the neck she glimpsed in the dreamlands, just before she fell. Could the Dead Men’s Ball, where the spooks and ghosts of the Hudson Highland gather once a year on Halloween to dance to the music of some very unexpected musicians, be the key to discovering the hanged man’s identity?
 
Lovecraft meets Narnia at Hogwarts.