Showing Succubus Heat by Richelle Mead

Georgina Kincaid has been a bad, bad succubus...which should be a good thing. But she's in a foul mood after breaking up with her boyfriend Seth and has been so wicked that über-demon Jerome decides to 'outsource' Georgina to a rival - and have her spy for him in the process.

Then Jerome is kidnapped, and all immortals under his control mysteriously lose their powers. With her life-sucking ability gone, Georgina finds herself caught up in a sinister plot.

Is she the only one who can stop all Hell breaking loose?