What would happen if a virus wiped out everyone who's gone through puberty be like? What  would life be like for the children left behind to fend for themselves? What drives the little lost children as they grow up and inherit the earth? 

Unbelievably sad, but in such a good way. I really enjoyed how Ammaniti tied together seemingly random pieces of information to create a rich world. So much happens in what isn't a very long book.