Three witches - Granny Weatherwax, Nanny Ogg, and Magrat Garlick - find themselves in a story that is essentially Macbeth, and they'd rather not. A duke has murdered the king of Lancre, and the witches have hidden the infant heir. Now the duke's paranoia and the kingdom's misery are growing, and the witches must decide whether to interfere with the natural order of things. Pratchett's love letter to Shakespeare, and the book that established the witches as a trio.