This is one of the Penguin box of YA advanced readers copies I got last month. The cover as you can see is very creepy looking, almost just like Rosemary's Baby.
Basically the premise is that this is a town where babies disappear out of their cribs all the time, only to be replaced with something that's not quite right. Normally these replacements die young, as what they are cannot deal with things in the normal human world. They're allergic to iron and consecrated ground and blood.
Our main character is Mackie. Mackie is a replacement who has somehow lived to be a teenager. He is allergic to all these things, but his family has helped him to survive somehow. He must make sure though that he keeps a low profile, as the town has in the past killed one other of these replacements for the kidnapping of the babies. It turns out Mackie is needed by these creatures, but the town needs him too. It is time for a sacrifice, and it turns out that it may be Mackie's friend Tate's younger sister that is the sacrifice. Mackie must figure out how to save her, as well as keep his secret from the town, and try to live the life of a teenager.
It is sometimes hard for me to get into YA books that have a male protagonist, and it was a bit at first with this. But once I got into it, I didn't want to put it down. I'm sure this will be a popular book with kids into this sort of story.