The Daylight Gate by Jeanette Winterson.
A gripping Gothic page turner about the trials of the Lancashire witches. Winterson's prose prove disturbingly grotesque and often the graphic description of real life destitution and poverty reads far worse than any deeds at the sabbat.
However witches and witchcraft are the crux of the story and the novel provides a historical social commentary on witchcraft and the real life persecution of witches or those thought to be witches.
The novel was published by Hammer and it would be fantastic to see this turned into a film (albeit watered down, there's a lot on offer here that would be a no-no for the BBFC)