Terry Pratchett takes Shakespeares Macbeth and Hamlet and then turns them up till the knob comes off. Its all there a wicked duke and duchess, the ghost of the murdered king, dim soldiers, strolling players, a land in peril. And who stands between the Kingdom and destruction? Three witches. Granny Weatherwax (intolerant, self-opinionated, powerful), Nanny Ogg (down-to-earth, vulgar) and Magrat Garlick (nave, fond of occult jewellery and bunnies). Three witches gathered on a lonely heath. A king cruelly murdered, his throne usurped by his ambitious cousin. A child heir and the royal crown, both missing. Witches don't have these kinds of leadership problems themselves - in fact, they don't have leaders. Granny Weatherwax is the most highly regarded of the leaders they don't have. But even she finds that meddling in royal politics is a lot more complicated than certain playwrights would have you believe. Particularly when the blood on your hands just won't wash off . . .