This is the third book in the Night Tracker series. In this book, the Vampires are tired of being looked down upon and being left out of paranorm governance. They have somehow discovered that the paranorm ruling council keeps a file containing detailed information about all paranorm races - including their weaknesses - in their archives...which is located right next to what passes for the paranorm official lock-up for their criminals. Smart move, keeping sensitive documents next to a prison.
The Vampires strike a deal with the Sprites to help them obtain the file. In the process, the Sprites discover something far more dangerous to paranorm existence, something which also eventually falls into the Vampires' hands. Nyx and her friends must recover the threats to the paranorm races and stop the Vampires from taking over.
Believe it or not, this series has improved with time. This book is still a by-the-numbers urban fantasy with predictable action, perfunctory dialogue, and little depth. However, we at least get to see Nyx experience some real emotion this time around, which is a nice change from previous books. She comes across less cardboard and more real.
As other reviewers have mentioned, the running joke about Nyx's skin being "amethyst", not "purple", wears extremely thin. Yeah, it was amusing the first couple of times she thought/said it in the first book; now, it's just irritating. Also irritating is the repetitive mention of her "cobalt blue hair", her "xPhone", her "Victoria's Secret" panties, etc.
Also, the Vampires are so unrelentingly, irredeemably evil that they come across as caricatures rather than actual characters. In my opinion, villians are much more interesting when there are shades of gray, when there is some complexity to their actions and motivations. That doesn't occur here.