This book was different than any of the other books in the series. The plots of the first three were "Here is the problem, let's solve the problem, let's introduce the killer, let's find the killer, found the killer, the end." I love books like that, but this one was different and it so far my favorite book in the series. Within the first 20 pages in this book we knew who the killer(s) was/were for the particular crime they were trying to solve. So what did they do with the other 400 pages? They created a problem out of the solution of most other mystery novels. Easy read but also had lots of twists and turns which made it a nearly impossible book to put down.