Mouse and Owl — Bracken MacLeod

Nergüi is among of the last of her tribe of nomadic people reluctantly living as refugees behind the walls of a fortified city. Isolated and grieving after the public execution of her lover, she despairs at the injustice done to him and dreams of revenge. But she is just one woman, and can't stand alone against the city's powerful elite. She has something they don't, however. She has ancient magic… … and she has the rats in her walls.