This is the fourth in the Georgina Kincaid series. She is a succubus, prowling the streets of Seattle, sucking the life out of men with her intimacies with them. This story builds on the three prior novels, reintroducing characters like Roman (her relationship with him in an earlier work ended badly, to put it mildly).
The major plot twist here is that the boss (a demon, Jerome) in the Seattle region disappears. The power of immortals (vampires, imps, and succubae) also disappears. They are immortal, but do not have their powers. If Jerome can't be found, then a new boss will need to be selected. Part of the driving force of this book is the dynamics of those who want to take over; indeed, ambition has led to something of a coup d'état.
Georgina, in an improbable alliance with her former boyfriend, Seth Mortenson (the dilemma that they faced--they could not be intimate without her slowly draining him of his life force), sets out to find Jerome. Adding to the dynamics of the work is that after their breakup, Seth began dating one of Georgina's best friends, Maddie (you need a scorecard to keep the players straight if you haven't read earlier works in this series; one piece of advice--read some of the earlier volumes to understand context).
There are the poignant moments between Seth and Georgina; now, they can be intimate without damage to him as she has lost her powers. But--there is also the knowledge that this is only for the short term and that they are both betraying Maddie.
The book ends with some unresolved tensions that promise to animate future volumes in this series. All in all, another fine entry in the series by Richelle Mead.