Map of Unknown Things series by Rod Duncan. Due out 14th Jan 2020 from Angry Robot, it's 400 pages and will be available in paperback, audio, and ebook formats.
This was a compelling read and a beautifully well engineered and plotted denouement to a really enjoyable series. It is ostensibly an alternate timeline fantasy but there are so many more themes explored here: the notion of family, loyalty, personal freedom at what price, and always against a backdrop of war and espionage. The prose is evocative and immersive. There were several times while reading that I looked up to find that I had been completely unaware of the passing of time and an hour had slid by unawares.
It had been a while since I read the other books in this series and I didn't have any trouble following the plot. I suspect it would work fine as a standalone (but I strongly recommend the author's other works, so read them all).
I like the intelligence and fearlessness of the twin protagonists. This is quite a personal story, set against a background of politics and war.
Definitely one of my best reads this year. Five stars.
Disclosure: I received an ARC at no cost from the author/publisher for review purposes.