Shrill Dusk (City of Magic) by Helen Harper

Charley is a cleaner by day and a professional gambler by night. She might be haunted by her tragic past but she's never thought of herself as anything or anyone special. Until, that is, things start to go terribly wrong all across the city of Manchester. Between plagues of rats, firestorms and the gleaming blue eyes of a sexy Scottish werewolf, she might just have landed herself in the middle of a magical apocalypse. She might also be the only person who has the ability to bring order to an utterly chaotic new world.