I've been reading this to sleep but end up staying up really late to finish this. It started like any average start with a guy suddenly surrounded by the supernatural and end up turning into one himself. But then there's a lot of twist in this book that I could hardly wrap my head around. Everyone isn't what they seems, there were some caveman phrases somewhere that should be laughable if death doesn't hang around the person who said them. 
 Purgatory is a slightly different than the Bound series. Yes, both have the same vampire and werewolf coupling but its about a special group in law enforcement handling the paranormal cases rather than werewolf clans fighting for their territories. The romance is quite a secondary part of the book as the story focus more about Duncan's transformation and his family history and Holly's own secret and the lies people kept from her and the whole premise centered on trying to find the werewolf serial killers, double agents and the things trying to make things break all supernatural hell loose among the population. 
 There's quite minimal sex scenes in this book to constitute as full-on supernatural smut and even without the explicitness, the book is a good well-written horror mystery thriller on its own. There's a lot of gore and deaths to keep the blood racing and more character development between the characters that made them interesting other than their attraction to each other and I think pre-existed attraction help with the book as it keep up with the novel's pacing. Its a solid Urban Fantasy novel even if it look like a bodice ripper.