This is more of a 3.5 then a 4 but all in all a good first book and an enjoyable read.I started out with the audio for this book, which I do not recommend. The narrator was not great with any of the accents and while she was not reading in a monotone, it more just matter of fact...there were no inflections or emphasis in her speech....and it made the story slow and boring to listen to. I returned the audio and picked up the book to finish Edie's adventures as a Y4 nurse. I wish there was a bit more world building, because it is not 100% clear to me if the supernatural world is "out" or not in parts of the book it seems like they are and in others it seems like it is still a secret and only some know...which is not really a big deal I guess other then my need for details.So, the world building was okay...I liked Edie and her coworkers in Y4 were interesting. A zombie boyfriend was kinda ewww .....because generally when you think or read of zombies you think the mindless decaying dead which is not quite the case here....I am looking forward to the next book in the series.