Eva Ibbotson

Fredegonda, Goneril, and Drusilla are Great Hagges, much more important and much rarer than regular old hags. They think that ghosts these days are decidedly lacking that people haven't been scared of ghosts for years. So one day they decide that something needs to change - it's time for these ghosts to learn a thing or two about being scary. And what better way to teach them than to set up their very own school for ghosts?