It was hard to be frightened of the unknown when the unknown kept chickens. [p. 66]
Marra is the youngest of three princesses. Their mother has made politically advantageous matches for the elder two: first Damia, who married Prince Vorling, and then Kania, who marries Vorling after Damia's early death. Marra -- who's been packed off to a convent, nicely out of the way of politics, where she has learnt to midwife and to embroider -- learns that Damia's death was suspicious, and that Vorling is immensely cruel to Kania ... and will be until she produces an heir. Marra realises that nobody else will save her sister, or herself: and sets out to find a dust-wife (a graveyard witch), and perform three impossible tasks, and then quite a few more tasks that seem even less feasible.
Nettle and Bone opens midway through the second of those tasks. Marra is making a dog out of bones, and her fingers are sore from weaving her cloak of nettles. Worse, she's in the blistered land, where the folk are mostly cannibal zombies. This turns out to be irrelevant to the wider plot (well, Bonedog is extremely relevant) which sees Marra and the nameless dust-wife venture to the goblin market, to the run-down home of a fairy godmother, and into the necropolis beneath Prince Vorling's palace.
The story is told from Marra's point of view. She's thirty, somewhat naive, often afraid and yet determined to save her sister and her kingdom. Hers is a particular kind of courage, but it's as fervent as that of Fenris, a former paladin retrieved from the goblin market. They travel with the dust-wife (who is utterly fascinating because Marra knows little, and understands less, about her) and, later, Agnes, Marra's own fairy godmother who is ... perhaps not the most powerful of her kind. Oh, and a hen possessed by a demon: when it casts a shadow, the shadow has little horns. The hen is mostly harmless, at least to the protagonists, but there are vengeful ghosts, a Boschian horror called the Tooth-Dancer, a woman ridden by a wooden corpse-child, a woman doomed to immortality. These are treated as matter-of-factly as more mundane horrors: poverty, violence, fear of outsiders, prejudice.
While this story is firmly rooted in fairytale, it also interrogates the tropes of that form. As the dust-wife says, “Fairy tales ... are very hard on bystanders. Particularly old women." The handsome prince is the villain; fairy godmothers lay curses, not blessings (though, per Agnes, "There’s only one story about godmothers that’s always true. Bad things happen if you don’t invite us to the christening"), those who are abused will often cling to their abusers, and princesses live circumscribed lives without privacy or power. Marra's down-to-earth personality and determination to be a decent person is the perfect foil to the darker aspects of the story, and her particular gifts are essential to the happy ending.
I have to say I didn't enjoy this as much as some of Kingfisher's other work: I think that was a case of 'right book, wrong time', because I've skimmed it again while writing this review and am now tempted to reread!