I first heard of this book from the creepy adverts for it on TV, the description sounded haunting, promising. Ordinary kids living ordinary lives, only for everything to change. Adults gone, reduced to slavering zombies eager to kill and eat the kids left behind.
Set in London, Higson's writing bears a lot in common with his contemporaries Anthony Horowitz and Garth Nix - it's got that youthful snappiness to it that grips you from end to start. It's quick, witty and in terms of the kids' dialogue, feels very natural. Crucially in this novel, you are made to really feel for the kids, to put yourself in their place (something aided by some wonderful description) - and thus, it's even more horrific when any of the protagonists are killed.
We are presented with a ruined city left in tatters, a year after all adults have suddenly transformed into shambling diseased hulks. A handful of kids, mainly ranging from 8-15 are left to scavenging homes and supermarkets to eke out an existence, constantly on the run from the `grown-ups'.
In time they are tempted away to seek out Buckingham Palace after hearing that it is apparently `safe', the promise of a better life proving irresistible to them. We are given an account of their dangerous journey across London, only to find when they finally arrive at the palace, that all is not quite what it seems. There's a strong essence of some of the themes of Watership Down here, the book as a whole coming out as a kind of mix of 28 Days Later and The Lord Of The Flies. And it works to perfection.
The relationships between the kids, from the bonds built up as they try to survive, to the opposite side of the coin - the conflicts when opinions clash. This in many ways lies at the heart of the novel, human notions like greed often leading to awful consequences as the protagonists are in turn tempted. If there's one criticism, it's that the ending is very open and a lot is left completely unresolved - although this is most likely due to the fact the ending leads on to a sequel.
All in all though, The Enemy is a thrilling book - scary, moving, dramatic, action-packed, everything you want in a teen novel.