This is Book 3 in a series. I recommend that you have read the others in order to best understand what is going on.
I loved Book 1 and 2 and was eagerly awaiting Book 3. It did not disappoint.
Again, I marvel at the imagination needed to create whole systems, societies, communities, places etc. And to be able to keep track of them. This story is relatively complex (but quite easy to understand when you have just reread the other 2 to remind yourself of who is who etc).
The story continues with Sloane working with her newly found family to root out The Order, who are intent on destroying the Protectors. It kept me on my toes with pronunciation – as it uses a lot of words based on old English and Scottish Gaelic. Luckily Dorothea also helped there teaching Sloane how to pronounce the words correctly in order for the spells to work.
There is a lot of loss and grief in the story – but the story is so good and not gratuitous. The exploration of grief acknowledges that we do not just grieve the dead – but for loss and life that we have not lived and experiences with our loved ones that we missed for whatever reason. Even when your life is surrounded in magic – you need to enjoy every moment because you never know when it will all end.
It is also a comment on society as a whole – as in order to identify the evil bad guy the first place Sloane looks is to families that have amassed an excessive amount of wealth and land. Very apt today.
Hopefully there will be a Book 4 and we will see Sloane and Rose find Dorothea and fight on.

So yes. I most definitely recommend that you read this series.