The Aching family have lived on The Chalk for centuries. They're sheep farmers and Tiffany is the youngest daughter. Like Granny Aching before her she's quiet, a thinker, and possibly a little bit of a witch. Down by the river one day Tiffany sees a couple of very small blue men, just before something green and nasty rears out the water in front of her. Tiffany goes home to think about this and then comes back and uses her little brother as bait. The monster returns and Tiffany whacks it with her weapon of choice, the frying pan. Miss Tick, an actual witch, is watching from Another Place and is unable to believe her eyes. The Chalk doesn't breed good witches but it seems it has. Tiffany learns from Miss Tick that her life is in danger from something that is happening in her world and that that 'something' is leaking in from another world. The Wee Free Men are there to help her, not that it's help any normal person would choose, but beggars can't be choosers - not when your younger brother is stolen away and no one else has a clue where to look for him. Things are about to get very sticky indeed...
I can't think why I haven't read this Pratchett series before as I've read so many other Discworld novels. I had the sequel to this first book, A Hat Full of Sky, but not the first book itself, so had to borrow it from my daughter. I'm so glad I did. All the wonderful Pratchett humour is here (talking about the travelling teachers):
They went to sleep under the stars, which the maths teachers would count, the astronomy teachers would measure and the literature teachers would name. The geography teachers got lost in the woods and fell into bear traps.
Perhaps the 'geography teacher' thing is a purely British joke - it certainly made me giggle - and I continued to laugh all the way through, cheering Tiffany on and adoring The Wee Free Men and their antics. The ending is wonderful too as two much loved Discworld characters make a brief, but satisfying, appearance. It's no exaggeration to say that I absolutely loved this book and have already started A Hat Full of Sky and plan to read Wintersmith, the third book, pretty soon after.