Small Favor (The Dresden Files #10)
No one's tried to kill Harry Dresden for almost an entire year, and his life finally seems to be calming down. 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. It's a small favor he can't refuse...one that will trap Harry Dresden between a nightmarish foe and an equally deadly ally, and one that will strain his skills- and loyalties-to their very limits.
It figures. Everything was going too well to last...