Wyrd Sisters (Discworld)

Terry's Pratchett's profoundly irreverent novels are consistent number one bestsellers in England, where they have catapulted him into the highest echelons of parody next to Mark Twain, Kurt Vonnegut, Douglas Adams, and Carl Hiaasen.
Meet Granny Weatherwx, the most highly regarded non-leader a coven of non-social witches could ever have. Generally, these loners don't get involved in anything, mush less royal intrigue. but then there are those times they can't help it. As Granny Weatherwzx is about to discover, though, it's a lot harder to stir up trouble in the castle than some theatrical types would have you think. Even when you've got a few unexpected spells up your sleave.