Grave Mercy, Robin LaFevers
Ismae is a peasant girl living in 15th Century Brittany. Just after her wedding to a violent pig farmer, Ismae is rescued by the herbwitch who tried to poison her before she was born (but you wouldn’t quibble: the pig farmer is horrid) and whisked away to a mysterious convent. The sisters of the convent of St Mortain aren’t your average nuns. Mortain is merely masquerading as a saint: he’s an ancient god; Death, actually. Ismae is, she learns, a daughter of Mortain; immune to poison and with a natural gift for killing, and the sisters are assassins, using their skills to ensure the Duchy of Brittany remains independant from the looming, malignant France.
That’s basically the background to Grave Mercy, the first book in the His Fair Assassin series, which is getting great reviews from the lofty New York Times to blogger-reviewers, like here or here. I read the whole book in pretty much a day. It’s an action-packed historical novel with some romance, mystical magic, and a few gory endings, and I liked it!