I liked this, mostly. The POV changes were too much, they changed a lot and even to the POV of secondary characters, which I hate.
The mystery was one of the weakest I've ever read. They are on case 14
and each one has had a letter from the same guy and they just now decide maybe they should look into why all of the murders/kidnappings victims have the same letter? Seriously? is that something you should have looked into after the first case? its an investigation don't you interview people, especially ones in recent contact with the victim? (view spoiler)[ then turns out the bad guy kills the parents and sells the kids on the Silver Market because the MC turns him down. So everytime he gets rejected he kills/kidnaps families to hurt the MC who didn't even pay enough attention to know what was going on. He knew his files were being tampered with but didn't care enough to find out why. yeah pretty weak all around (hide spoiler)]
i didn't see the connection between these guys, it was like hate you but you're hot to love you you're hot. It was just like huh when did that happen?
And the whole Blue Flame thing what was the point of that? it never came into play and it didn't seem to make him a better investigator or anything