Ok this book picked up the pace from the previous; whereas the 3rd book felt like a drag with the cast figuring out that Matt wasn't himself. It wasn't "BAD" just annoying at times. We call that dramatic irony where the reader/viewer knows more than the cast if I'm not mistaken.
Matt is finally ok, and now we're deep into unraveling of the threat to the kingdom of the known lands. Our new young king is on a mission to find out the source of the corruption, and although not as vicious as when under the control of Emma; Matt now knows that sometimes a heavy hand is needed to get results. He's now a long way from when we first met him in the 1st book, and it's great to see him stop whining like he was back then. Granted he's still a teenager, and not 100% confident in himself, or his actions; he's become more decisive in taking action than he was before.
Chal, and Priest get some more time together as they investigate a [what would appear to be] returning vigilante-like group of "assassins/thieves" known as the Crimson Wolves. The Crimson Wolves having become a long distant memory within the kingdom as they haven't been around for almost 20 years, and are now implicated in some attempted assassinations in the castle. It's a great line of storytelling that fleshes out not just the world of the Known Lands itself, but of another threat to the kingdom besides the ever present Fey. We thought the threats from within had been dealt with only to encounter another. Not to mention one of the least likely characters you might imagine having ties to the Crimson Wolves. It's also a great time to see Chal try to work alongside Priest whom after the events of the 3rd book seems to be coming apart at the seams. Yes the same Chal whom had been outwardly vocal at Priest's "lecturing," and general overly positive outlook on life now has to try, and manage a Priest who has lost his faith.
Maeve's storyline of seeking out the Assassin's guild for answers regarding the aforementioned assassination attempts is great as well since we get to see a new dynamic within the Guild itself. Her investigation will not come without it's own cost. Her motivation stemming from the fact that her newfound love for Chal, and the possibility of losing that if he were to die is heartwarming. I don't know about anyone else, but I didn't think at the outset of the series that I would appreciate a romance subplot, but with Chal & Maeve it just works. They've been through hellish times in the past, and in the recent events of the series itself that I'm rooting for them to have a good ending after it's all said & done.
We get more interaction between Cutter, and Feledias as they traverse the Blackwood. I mentioned in my review of the 3rd book that I really like the way we were getting more development of their relationship, and their journey in this book is all the better. It feels like their part in the story is put in a bit of the background as the other two storylines take a more central narrative. That's not to say nothing happens with the brothers, as we get more insight into Feledias' own troubles, and sense of guilt over past actions in this book, as well as Cutter finding common ground with his once estranged younger brother. However the meat 'n potatoes of this book would seem to be the Crimson Wolves, and Maeve's dealings with the Assassin's Guild which is good, but I'm hoping the brothers' journey gets more attention in the last book. Given where their story leaves off at this books ending I would "bet the farm" they're going to be a huge focus.
I'm almost apprehensive to go to the next book, because I want to continue these characters' stories, but with the world of the Known Lands being such a grim place I can only imagine we won't get a happy ending for everyone involved. We'll just have to read on, and find out.