I probably missed something, but there is a problem with continuity in this book. At least 3 characters appear who according to Dresden's flashbacks should be playing major roles in the previous two books, but they were NOT there.
Anyhow, to the plot: the ghosts are very restless in Chicago, and Harry Dresden and his sidekick (the one who was not mentioned before) have their hands full dealing with them with no time to spare looking for the person who made them restless in the first place. On the top of that, Harry receives an invitation to a vampire party. To go to such an even is never a good idea (even if one is a vampire, it turns out), but not to go would have some bad diplomatic consequences.
This is a good, fast-paced book. My only complaint - other than the one mentioned in the beginning - I am getting a little tired of Dresden's narrow escapes from danger on almost every page; they are getting a little cliche. Still, I enjoyed the book which deserves 4 stars.