Uprooted by Naomi Novik

This one's getting a lot of chatter for the Hugos this year. Novik wrote the excellent Temeraire alt-history novels about dragons in the Napoleonic wars, and this is a more adult-themed fantasy novel. It's supposed to be awesome, and given how great His Majesty's Dragon was I don't doubt it at all.

From Amazon:

Agnieszka loves her valley home, her quiet village, the forests and the bright shining river. But the corrupted Wood stands on the border, full of malevolent power, and its shadow lies over her life.

Her people rely on the cold, driven wizard known only as the Dragon to keep its powers at bay. But he demands a terrible price for his help: one young woman handed over to serve him for ten years, a fate almost as terrible as falling to the Wood.