This is a great retelling of a classic tale, Beauty and the Beast. (I give it [the first book, Depravity] 4 not 5 stars only because the tale is chopped into 3 books.) 
 I'll compare Depravity to Stephen King's retelling of the story of JFK's murder in 22-11-1963. Everyone (of my generation, anyway) knows all the details. Down to what Jackie was wearing and that Senator Connolly was shot, too. How could King possibly come up with a fiction tale to hold one's interest when we all know the outcome? Well, he did, in a gripping way. 
 The same is true of Ms. Haag's Beastly Tales books. She has taken the essentials of the tale and given them creative and original new life, with more edge. Beauty (here called Benella) has much more agency. I say books; I've only read Depravity so far. This first third of the tale is not erotic. If it were a movie, it might be PG-13 except for two brief scenes that Beauty witnesses and a few scattered references to lustiness. Well, maybe R. Definitely R. Now that I think about it, there is a scene with ... well, let us just say lots of nubile women. Not dark, however. 
 Lots of plot twists within the ambit of the original. 
 If you read the first - which I urge that you do - be prepared to buy the next two. I'm half way through the very short second book. 
 My disclosure: I don't know the author and I wasn't asked to review the book.