Jacquelyn Frank's The Nightwalkers series has focused on various Nightwalkers (Elijah, Noah, Damien, etc.) and their search for mates. In the last couple of books, there has been mention of the 'Shadowdwellers' - another race of beings not really mixing with the rest of the things-that-go-bump-in-the-night. Ecstasy is apparently the start of a new series which focuses on the Shadowdwellers, with just a few references to the Nightwalkers (and a brief appearance by one of the heroes of the previous series). This means that Ecstasy works very well as a standalone book and that there's no important information carried over from the previous series.
The world of the Shadowdwellers is very interesting: they have reality
('realscape') but also a sort of alternative reality ('shadowscape'), which is a version of reality but without people and light. The Shadowdwellers can visit Shadowscape, but not for longer than a few days as it engenders a euphoric effect which can significantly harm them. As the book starts, Trace, an important political figure in the Shadowdweller world, is visiting Shadowscape in order to battle a traitor. As he fights this traitor, he sees a woman - one of the 'Lost', spirit-beings with no consciousness who are remnants of people in comas in the real world. However, this 'Lost' person can clearly see and hear Trace, something that has never happened before. Not only that, when Trace is mortally wounded, this woman, Ashla, is able to heal him.
Trace knows that Ashla can only exist in Shadowscape and that he can't safely stay there very long. However he is intrigued by her; when he is forcibly dragged back to reality, the world in which his political expertise is required to maintain the safety of the twin regents of the Shadowdwellers, he fears he won't see Ashla again. But Ashla is unique – she may be an important figure in Trace's life, as well as someone who can keep him and those he loves safe in other ways.
Jacquelyn Frank lyrical prose style is far more interesting than one often finds in this genre. Her descriptions of Shadowscape are particularly effective, as are those of Ashla's confusion at finding herself in this grey and lonely world. Slightly less successful for this reader were the characterizations of both main characters, who feel one-dimensional. However, I very much enjoyed reading Ecstasy. Although it doesn't tie up all the loose ends, presumably as a springboard to the next in the series, it’s a really interesting and often original read.