Finished the book yesterday. I'll try to keep this spoiler-free, but we'll see how that goes.
The Traitor Baru Cormorant opened with a simple, yet devastating statement: This is the truth - You will know because it hurts.
The Monster Baru Cormorant opens with a similarly simple, yet devastating counter: If something hurts, does that make it true?
Right off the bat (hah), let me make a simple statement myself: These rank in the top 3 book openings I know of (right behind "The sky was the color of a television tuned to a dead channel" and "The Moon blew up, with no warning and no apparent reason", bonus points for anyone who knows where those came from). They perfectly encapsulate the books they're attached to; Traitor puts Baru through a lot of torment (most of it seemingly self-inflicted), in Monster, Baru is forced to deal with the fallout of her previous actions, as well as the creeping realization that a lot of her fundamental truths may not be so true.
But, plot. In the aftermath of the failed revolution Baru orchestrated, she was elevated to the rank of Cryptarch of the Falcrest Imperial Republic. Now part of the power behind the throne, she is sent on a mission, together with her two best frenemies, to root out the Cancrioth, the rumoured power behind the throne of the Oriati Mbo (Falcrest's greatest rival amongst the nations of the Ashen Sea).
But since this is the Baruniverse, nothing is ever simple. Baru's machinations during the Aurdwynn uprising come to haunt her: Both figuratively, in the form of a deep depression over having to disavow and kill her lover Tain Hu and about betraying everyone who ever trusted her, and literally, in the form of Tain Hu's cousin Tain Shir.
Tain Shir, it has to be said, is terrifying. She was, once upon a time, a protege of the same master Baru is serving, but fell from grace: Now, she is an instrument of revenge. Her presence in the book is similar to Anton Chigurh in No Country For Old Men: A force of nature that can't be reasoned with, can't be contained, only evaded (for a time).
During her mission, shenanigans are had, new allies are met, and alliances and power balances shift around. It is, as usual for Batts, an engaging and gripping read, but there's a few caveats I need to add here before finishing with effusive praise:
1. Monster, unlike Traitor, is not a standalone book. Not just in terms of it being a sequel, but also in terms of it ending on a sequel hook (Battuta just wrote too many ~words~ for this one, so this book had to be split up); this is not a dealbreaker for me, obviously, and loyalty to Batts compels me to ask you for forbearance from anyone for whom it might be: If you wait for the sequel to come out to buy both books, it's bad for the vital statistics driving Batts' income.
2. This book is, at times, an oppressive read. Not only does Baru's depression hit her hard, and us with it as we spend time in her head, but her ingenuity and resourcefulness as established in Traitor don't really get much screentime either. She has her moments, to be sure, but ... there could've been more of them for my liking, y'know?
That out of the way, effusive praise time: I love this book. By making it into a road trip, we get to see many more corners of the Baruniverse, much more of its cultures and their fascinating beliefs and practices. By having interludes from other character's POVs, we get a better picture of who Baru is, how she presents herself, and how she's seen by others, and each of the other POV characters is interesting in their own ways. As any good middle entry in a series, it leaves me both satisfied and intensely hungry for more.
TL;DR: Buy this. If only for the absolutely gorgeous cover.