Wyrd Sisters

This novel has also been translated into an animated mini-series available through Acorn Media. While the quality of the animation is acceptable it is not the greatest out there.

The story bears a very strong resemblance to a certain Shakespeare play involving a king, his ambitious brother and the brothers very demanding wife. After the king dies of natural causes, since a dagger in the back is natural causes for a king, the brother takes the throne and the prince is smuggled out of Lancre by our favorite witches.

The mini series stays very close to the novel, plot wise, and the voicing is good though the it can get sort of muddled and garbled in sections.

Yes, it is true that the Wyrd Sisters did present a supernatural element to Shakespeare's Macbeth, as Triune pointed out. They took the form of oracles, alternately encouraging Macbeth to kill King Duncan and take his throne, and telling him that he will be killed by a man not "born of a woman."(Act 4, Scene 1, line 80)

The other intersting aspect of these charcters is that Wyrd means "fate." Essentially, the three sisters of fate, as depicted in Norse mythology as well as Greek mythology desided to pay a visit to Scotland and ruin Macbeth's life. Before he met these sisters, Macbeth had been a good and loyal subject, and had never considered killing King Duncan. Once this idea was in his head, however, he killed his king. When the sisters told him to beware of Macduff, Macbeth had thieves kill Macduff's wife and son.

Macbeth's ambition coupled with his wife's scheming ultimately fated him to die the way he did. Macduff eventually returns, and kills Macbeth. If anyone is wondering how Macduff could not be "born of a woman," the explanation that Macduff gave was that he was "from his mother's womb untimely ripped." (Act 5, Scene 8, lines 15-16) Apparently according to Shakespeare's logic, having a C-section did not count as childbirth.

This is the first of Terry Pratchett's wonderful sequence of novels about three witches in the remote mountain kingdom of Lancre. In their first outing they have to deal with kings and ghosts of kings, in a plot not unlike a certain Scottish play. Technically an earlier novel, Equal Rites, comes first, but it's not necessary to have read that or any other Discworld book in order to enjoy this. If you haven't read any Pratchett before, here is not a bad place to start.
Great fun, wise and laugh-out-loud funny, it's a book I warmly remember, even after several readings. The two books that follow - Witches Abroad and Lords and Ladies - are even better, and along with the early Guards books (Guards! Guards! and Men at Arms) probably represent Pratchett's best work.