Until now, any Discworld book relating to witches tended to be set in Lancre.
Now we moved onto the chalk downs (a lightly veiled Wiltshire or Dorset) in order to follow the story of Tiffany Aching.
Tiffany was just nine years old when a fairy stole her baby brother. She followed them into Fairy Land, armed with just a frying pan, to take on the Fairy Queen Herself.
What follows is a coming of age tale spread out, so far, over four books.
Though aimed at young adults, they are some of the most remarkable tales that Terry Pratchett has ever told. I know plenty of grown adults who would say that they are his best; and I count myself amongst them.
The Chalk doesn't really have witches. Tiffany's late grandmother was a Shepherdess. She was the witch that they don't have. This unspoken fact was acknowledged by all.
Primarily it was known by the Nac Mac Feegle. They weren't so quiet about it, having a propensity to yell such things from the hilltops. Fortunately they can hide behind blades of grass, so their yelling goes largely unheeded.
They are fairy folk, but they owe their heritage to a very stereotypical view of HIghland Scots. Imagine if the entire cast of Braveheart had shrunk down to a few inches high and believed that they were dead.
The dead bit is important, as they think they're now in Heaven. With all of the alcohol and fighting, it has to be Paradise, right?
When Granny Aching - their Hag of the Hills - died (or, from their point of view, stupidly got born back onto Earth again), the Nac Mac Feegle started looking out for her successor. They spotted Granny Aching's own small grand-daughter taking on the Queen of Fairy with a frying pan.
It was a fair cop really.
They are determined to 'help' (in the broadest possible meaning of the word sometimes) Tiffany fulfill her destiny to become a witch on the Chalk. That includes watching over her, as she travels away from home, to learn witchcraft in the Ramtops.
Through Tiffany's eyes, we meet hundreds of witches. A dozen or so become quite major characters, acting as her mentor or her peers and their mentors. There aren't just vague references here, we discover precisely how Discworld witches are trained; and we get to attend the Witch Trials with them.
(Incidentally, Witch Trials there aren't nearly as scary as in our own world. It's more of a competition to see who has the best spells, rather than the whole burning at the stake thing.)
But one witch above all stands out as one of the most influential in Tiffany's young life.
That, of course, is Granny Weatherwax herself.