Cold Days by Jim Butcher

In this book Harry Dresden is back from the dead and stronger than ever--thanks to his agreement to serve as Queen Mab's Winter Knight. Harry has got to figure out how he can serve in this role without letting it corrupt him--but in the meantime, Chicago is likely to be at Ground Zero of a magical explosion of apocalyptic proportions (centering on Demonreach, of course) and Mab has given him his first assignment: kill her daughter, Maeve (an immortal, for those of you keeping score at home). I like the way that this book doesn't shy away from tough questions, or asking Harry to do morally questionable things. I think Butcher has done (and continues to do) a great job increasing the stakes so we see what's going on with the series long term (it's not just one adventure after another) while making each book individually great to read.