The whole Poisonverse series is intense, and it's one of those series that has multiple authors, and even though they play off one another, they can be read out of order. I picked up this book randomly, and it was perfect and dark, but there were things here and there that I needed some clarification on. I chalked it up to this being the fourth book in the series. 
I loved how the mistaken identity worked in this one because it was intense, and it was crazy. I just had yet to find out who was going to find out first and what was going to happen once they did. I really loved Ruby. She's been through so much, but she never stopped fighting. But like I said, this book was dark, and it was heavy. I have read one other book in the series so far, and it does follow the same theme. It's not one that I feel like I could read back to back without needing a break because it seems like all the books go to a super dark place, and they're just heavy.