I forgot what happened in the previous book.
I think the reason Cat and Bones are no longer like they used to be comes from the fact they are now married. Before, they used to argue and there was that tension there that was fun to read. Now, they get along and everything seems "rosey."
This newest adventure involves calling on the resources of past characters to help solve the problem at hand. And how convenient was it for them to be there to help. If you read the previous books, including the books that are supposed to be spin-offs, you already know who they are and Frost doesn't have to go into detail explaining them. It also introduces us to some new people. One is friend and the other is foe. I'm hoping the foe turns out to be bad enough to bring back some of the spark experienced in the first 3 books of the series.
I'm still trying to figure out how this book has anything to do with the overall story line, if there is an overall story line anymore.