To Shoot or Not to Shoot

Would like to give this more than 3 stars - call it 3 and a half. About a third the way through I got bored and started skimming it but once I figured out where the book was going I re-engaged and read it with real pleasure. Possibly my own inattention early on got in the way. It was the adult characters in the later timeline that came alive to me and it was that and the sense of an alien world right alongside our own world that I liked so much. The book slips cleverly between genres - I'm still not sure if the later time is meant to be our own world or a frightening parallel universe - could be read as either.