Overall 4-4.5 stars for this book - it was full of action and mystery and the characters are interesting.I won't do a summary here because I don't want to give anything away. There are a lot of Rephaim introduced in this book. I enjoyed the story behind the story here. Yes this book is about fallen angels and how the race of nephilim were created but behind that is the story of Gabe and Jude. The mystery of what happened in the year that Gabe wasn't at The Sanctuary, what became of Jude and ultimately, what did they do/find that could impact everyone.The main character Gaby/Gabe/Gabriella is interesting. The book opens with a bit of her back story (horrible accident) and we get a glimpse of who she is. At a glance, it appears she has had a rough time over the last year but she has made a friend (Maggie) who is wholly supportive of who she is and anything she does. Gabe is tough when she needs to be, has the right mix of sarcasm and sense of humor, and truly values the friendship she has with Maggie. Rafa is a great character. It is clear he cares for Gabe and truly misses Jude. Even though he tries to play at being detached from everything, he does care and wants to find/help his friend. I am curious to see in the next book if the past between Rafa and Gabe is revealed. Something definitely happened and I can't wait to find out what it is and how it affects their relationship.I enjoyed the other characters as well (Jason, Daniel, Daisy, Nathaniel, etc.) and look forward to learning more about them as the story progresses.I thought this was a great first book in the series and found myself unable to put it down - if you like a lot of action/fighting, some mystery and a fast paced story, you will enjoy this one.