When the King of Lancre dies of natural causes (a dagger in the back is, for a king, natural causes), the evil Duke Felmet takes the throne after the king’s rightful heir mysteriously disappears into the night. But the kingdom isn’t happy about this . . . and neither are the local witches who, against all tradition, decide to take it upon themselves to meddle.

In a hilarious parody/tribute to Shakespeare, here you have the main stories of Macbeth, Hamlet and King Lear mashed together, sprinkled with awesome Discworld characters and seasoned with an enormous measure of Pratchett humour. There’s a vengeful ghost, a ‘play within a play’, a dramatic death and a wicked tyrant who just can’t seem to scrub the blood from his hands no matter how hard he tries, a la Shakespeare. Throw in three bickering witches, a group of travelling players led by a dwarf, an evil cat named Greebo, and a Fool who has been taught that humour is in fact not a laughing matter, and you have all the essential ingredients of Wyrd Sisters. Oh, add to this a bunch of famous quotes taken directly from Shakespeare, but thrown into a context where no one responds appropriately. The Duke’s desperate queries of “Is this a dagger I see before me?” are met with confused responses by those around him, and the witches’ mantra of “When shall we three meet again?” sparks somewhat un-eldritch replies along the lines of, “well, I can do next Tuesday.”

Wyrd Sisters boasts the most coherent plot of the series so far, despite being crammed with typically bizarre yet hilarious Pratchett moments, such as the old witches experiencing the theatre for the first time, a mad duke wearing a white sheet and insisting he’s a ghost, and Death getting stage fright. It’s fast-paced and focused and funny, and I whizzed through it in less than a day. Best of all, it stars Granny Weatherwax in her first appearance in the Discworld series since Equal Rites, and she’s on mighty fine form. Along with her fellow coven members Nanny Ogg and Magrat, it’s up to Granny to use her wits, her defunct broomstick and her skills in Headology to save the kingdom from tyranny – but not before she’s learned a few things about the world, such as the meaning of ‘acting’ and how not to interfere with a live theatre performance (“He done it! We all seed ‘im! He done it with a dagger!”)

As is often the case with Discworld novels, one of the things that brings Wyrd Sisters to life is the cast of supporting characters, most notably in this case Nanny Ogg. Nanny is ancient, runs her own little empire of sons, daughters-in-law and grandchildren, and thinks that actors come from a faraway country called Thespia. When locked in a dungeon and threatened with torture she passes the time by playing ‘I-Spy’ with a ghost. She has no teeth at all, is fond of a drink or three, and is known to burst into cackling song whenever she’s had one too many apple brandies, some of her favourite ditties being ‘A Wizard’s Staff has a Knob on the End’ as well as the old classic ‘The Hedgehog can Never be Buggered at all’.

Wyrd Sisters is a rare diamond in that I thoroughly enjoyed it from start to finish, and is by far the strongest Discworld instalment so far.