Poison Study is like Butterfly's Dust. You will always keep coming back to it- if only to avoid the nausea and pain of not being able to read through its pages- and you wouldn't know how to escape. The world Maria V. Snyder created is compelling in its entirety as well as the characters. And the storyline. 
 Let's just say that this type of Butterfly's Dust is particularly potent. And you will find yourself poisoned by the desire to read more and more of this series. 
 It's fortunate that I like this poison then.