Small Favor by Jim Butcher

This book continues to indicate that something really wicked is coming Harry Dresden's way. When Queen Mab of the Winter Court of the Faeries calls in a favor, Dresden quickly finds himself up to his ears not only in the faeries but also Denarian schemings. I am continually impressed by Dresden as a character--he's not so good you can't stand him, and he's often tempted (and sometimes does) morally questionable things, but when the cards are all down, he comes out as a strongly moral character. I also like the way this series develops the big evil that Dresden has to fight: obviously it's bad, but it's not clear. Each mystery makes the plans and plots a little clearer, but we still don't know quite what we're up against. And I think that Butcher's willingness to let the readers find out with Dresden is one of the strengths of the series.