Monster High: Haunted.

Lurk what's waiting for the Monster High ghouls when they bring their killer fashion to the howlways of the spooktacular Haunted High! When the ghouls of Monster High follow Spectra Vondergeist one day, they discover a creeperiffic Ghost World with an all-spirit school. But their scary-cute student bodies are hardly welcome with the very strict Principal Revenant, and she punishes Spectra with frightful detention chains that prevent her from re-joining Monster High. Now, it's up to the imperfectly perfect friends to take on ghostly forms in order to save one of their own from disappearing forever!