I went into this book blind, only knowing of Daniel B. Greene because of a video he posted on YouTube. A Witch's Sin is at its heart a noir style detective story, but the setting is a post-apocalyptic cyber punk style world, in a megastructure similar to the building in the Karl Urban Dredd movie. Only this megastructure is hundreds of floors high with each floor being it's own "mini city" and the richer you are, the higher live in the structure. 
To add yet another twist, this world also has the supernatural: vampires are a part of everyday culture. One might think that with all of these elements in one story, that the writing would be convoluted or confusing, but Greene writes a compelling story that truly works. As our main character, Taya, attempts to solve the mystery of what happened to young Nita, the reader will feel the same tension Taya experiences as she struggles to know who to trust and what is really going on.