Summer Knight
In Summer Knight , Harry Dresden's past starts to catch up with him. There have been hints in the previous three books that Harry's past is not so pretty. He was orphaned at six and taken in by a wizard who trained him in magic. He fell in love with his foster sister* and, when the wizard turned out to be a practitioner of black magic, killed them both in a fire. Then he struck a bargain with a rather powerful faerie and has been trying to get out of it ever since. This was all peering in at the edges of the previous books, but now it becomes far more important. The faerie Harry had initially struck a bargain with ends up selling her end of the deal to the Winter Queen, Mab. Mab uses this influence to convince Harry to investigate a murder in Faerie and prove her own innocence. If he fails, the two sides of Faerie (Summer and Winter) are likely to go to war with each other. The wizards are also on his back to succeed so that they can procure Winter's help wi...