A fascinating idea, and fairly well executed in my opinion. The beginning of the book is my favorite, it reads like a survivalist adventure and a lesson in leadership and crisis management, then comes a post-apocalyptic episode complete with "UFOs" and men in strange suits, sneaking around with a handgun and infiltrating secret camps. Enter allies and strange doppelgangers, deception, doubt, and climactic deaths. Finishing off with boy meets girl. 
 All in all a good read. likable characters, and an excellent production by Audible. Good reading by both actors, I'm kind of in love with Nicola Barber's voice.