I read this immediately after book one (The Autumn Queen Protocol) and was just as swept along in this book as the first. The book could be read as a stand alone if you really must, but is far better paired with AQP. 
In AQP I found the shift between part one and two to be fairly expected. I didn’t predict it but it made perfect sense when it happened. Here I was like …oh. OH. Big twists in this one, really expands the world from before. We see the return of several major characters with new ones introduced. As always the characters are well fleshed out and multidimensional. Considering where we wound up at the end of book one this all feels very possible. 

I know major parts of this review are super vague but I really don’t want to do a spoilers cut and it is so much better if you discover it as it unfolds. You are really best not reading too many reviews and accidentally learning something at the wrong time on this one. If you like zombie books and especially ones with some pointed real world critique you will enjoy this book and should stop reading my review and go pick up a copy.