Bargain @ $1.99 from HarperCollins in Canada & the US (price should be the same at all the regular retailers):
The Last Witchfinder by Nebula & World Fantasy award-winner James Morrow (
ISFDB,
Wikipedia,
SFE), whose
Shambling Towards Hiroshima I quite liked when it showed up in the Hugo Voter Packet some years ago. This seems to be more a literary fiction-ish historical journey of self-discovery adventure with mild speculative/fantasy elements, but it placed within the top 5 on the annual Locus and Campbell Memorial Award lists (and also got a preliminary nod for the Tiptree, for Gentle Readers interested in potentially Gender-Bending SF which was the category it was nommed under), according to ISFDB. Apparently this was originally published in French translation, but then found an English distributor.
ETA: Wikipedia claims the story is narrated by a sentient copy of Isaac Newton's book
Principia Mathematica. I was going to buy this anyway, but now sheer morbid curiosity is bumping it up the TBR.
Jennet Stearne's father hangs witches for a living in Restoration England. But when she witnesses the unjust and horrifying execution of her beloved aunt Isobel, the precocious child decides to make it her life's mission to bring down the Parliamentary Witchcraft Act. Armed with little save the power of reason, and determined to see justice prevail, Jennet hurls herself into a series of picaresque adventures—traveling from King William's Britain to the fledgling American Colonies to an uncharted island in the Caribbean, braving West Indies pirates, Algonquin Indian captors, the machinations of the Salem Witch Court, and the sensuous love of a young Ben Franklin. For Jennet cannot and must not rest until she has put the last witchfinder out of business.