I always love a book that takes a known theme (angels, demons, fae, etc) and makes it unique - and this book definitely did that. Angel's have arrived on earth, and they're not friendly, and they are only a few as well. Demons have been on earth longer, living amongst humanity (although I'm a bit unclear as to whether that was always in plain sight, or hidden until more recent years), and are now roaming freely and controlling humans as they see fit.
In this post-apocalyptic world, Ruby is a fae in hiding, helping her human friends to survive while trying to find her sister. When she finally happens upon enough information to exchange with The Order for their help, her world turns upside down. Glamoured as a succubi, she is taken to the angel's castle where she should be able to learn their weaknesses so they can be killed. Faced with 3 deadly angels who question her identity and motives, she must now hold her glamour and keep her wits in order to survive. What she didn't expect was an ally from an unlikely source.
The storyline is gripping, the worldbuilding very well done, and the characters unique, intriguing and complex. I loved Ruby, but surprisingly couldn't help but also like Kratos and Adonis once we got to know them.