This book is a kind-of-but-not-really sequel to the trilogy in that it takes place after it, and I don't recommend reading it unless you've read the Black Jewels Trilogy. Obviously, it's not set on such an epic scale. The "plot" itself sounds rather silly: Surreal and her escort get trapped in a deadly(!) "spooky house" that was set up by a pompous writer who wants to get revenge on the SaDiablo family, and so, of course, Daemon and Lucivar have to do their "Evil Twin* Powers! Activate!" routine in order to get her out.
On a more serious note, it's really a story about what it mean to be Blood, and about some of the SaDiablo men's Issues. (Because there are very many.)
On a less serious note, read the book and marvel at Lucivar's awesomeness!
It was a fun, quick read, and for a while there, I couldn't put it down, but it kind of fizzled out at the end. Anne Bishop's bad guys are kind of underwhelming after a while. They're very easy to hate, which I guess is part of what makes the books fun. But, come on, how many tales about people exploding from sexual pleasure at the sight of Daemon and lazers shooting from Lucivar's eyes** do people need to hear before they realize that if you mess with the SaDiablo family, you're going to get your ass handed to you cheek by cheek, along with your other body parts. You'd think there would have been a memo going around by now.
Haha, this series makes me silly. I want more!
* And by "twins," I mean "half-brothers," but it just doesn't sound as cool.
** Kidding, kidding! He doesn't shoot lazers from his eyes. He shoots lazers from his hands.