"Summer Knight: Book 4 of the Dresden Files" by Jim Butcher
Ever since his girlfriend left town to deal with her newly acquired taste for blood, Harry Dresden has been down and out in Chicago. He can't pay his rent. He's alienating his friends. He can't even recall the last time he took a shower.
The only professional wizard in the phone book has become a desperate man.
And just when it seems things can't get any worse, in saunters the Winter Queen of Faerie. She has an offer Harry can't refuse if he wants to free himself of the supernatural hold his faerie godmother has over him — and hopefully end his run of bad luck. All he has to do is find out who murdered the Summer Queen's right-hand man, the Summer Knight, and clear the Winter Queen's name.
It seems simple enough, but Harry knows better than to get caught in the middle of faerie politics. Until he finds out that the fate of the entire world rests on his solving this case.
No pressure or anything...
I think pretty much all that can go wrong with Harry does. In this book Harry faces a rain of toads, a war between Summer and Winter, A hearing by the White Council which could result in his death, and to make matters worse an old girlfried shows up only to create problems.
The book opens up with Harry still trying find a cure for Susan his current love, and only the second woman he's ever loved. The cure is to cure her of vampirism. In the last book she was partially transformed into a vampire. He has let his hygiene go and his apartment's a mess. However he is getting help from the alphas, you may remember they are the group of college kids, oh yeah and they are lycanthropes.
Harry is soon hired by the Winter Faerie Queen to find out who murdered the Summer Knight. Everyone thinks it was the Winter Queen but she knows she is innocent and if the real killer is not found out there could be a war between the Summer and Winter Faeries. This could only lead to one victor and whoever comes out on top the world could either enter another Ice Age or a time of exponential growth. Now the growth may sound good but remember it also sounds good to E Coli and other bacterium.
This book is another turning point in the series in that Harry admits to Murphy everything there is to know about the supernatural world. Taking her under confidence to tell all the inside info Harry is risking a lot. However it is yet another time we see the almost human weakness of this wizard in that he needs outside help. Murphy is a bit taken aback but soon recovers and is there to help Harry in any way.
We are also introduced to members of the White Council of Wizards. There are some nice characters here including Harry's Mentor, Ebenezer McCoy. Ebenezer was Harry's assigned mentor after Harry killed his Uncle Justin. Also more of the story of Harry's falling out with the White Council and the Death (in self defense) of Uncle Justin.
Yet again another great book in what is turning out to be a great series of books. The humor in these books just makes them more fun.
