I Shall Wear Midnight

The fourth book in the Tiffany Aching series - five Discworld novels by master-storyteller Terry Pratchett.
Tiffany Aching is a witch alone.
Well, that's how she feels. Everyone seems so, apart. People respect her, but also fear her. There are loads of secrets she can't share.
And when the Baron dies, and Tiffany is framed for his murder, it's clearer than ever that she is, well . . . not liked
Now Tiffany must journey to Ankh-Morpork, to inform the Baron's heir, Roland, of his father's death. But on the way she meets something that likes witches very much . . . a bit too much - an evil ball of spite and malice that has only now woken up.
And is out to get witches everywhere . . .