Small Favor — Jim Butcher

The novels of the Dresden Files follow the cases of Chicago's only professional wizard, Harry Dresden, and his never-ending battle against the evil that plagues his world....

Harry Dresden's life finally seems to be calming down. The White Council's war with the vampiric Red Court has reached a period of tentative peace, no one has tried to kill him for almost an entire year, and the worst problem he's had lately is working out how to remove the stains on his carpeting. For once, the future looks fairly bright.

But the past casts one hell of a long shadow.

An old bargain has placed Harry in debt to Mab, monarch of the Winter Court of the Sidhe, the Queen of Air and Darkness -- and she's calling in her marker. Dresden still owes the Winter Queen two favors, and it's time to pay one of them off. Just one small favor he can't refuse -- one that will trap Harry Dresden between a nightmarish foe and an equally deadly ally and strain his skills and loyalties to their very limits.

It figures. Everything was going too well to last....