Wyrd Sisters

Wyrd Sisters is a fantasy book by Terry Pratchett. It was published in 1988 and it is the sixth book in the Discworld series and the first one to focus on the Witches.
Plot.
Granny Weatherwax, the witch who appeared in Equal Rites is the main character, along with the two other witches in her group. The story is a take on the Shakespeare play Macbeth.
TV adaptation.
In 1997, the book was made into a TV mini series.