Melanie is a little girl like any other she knows. She goes to school every day and she loves her teacher Miss Justineau. Sergeant Parks always comes to take her to school but she doesn't really like him much. Then, one day, Sergeant Parks doesn't take her to school he takes her to the lab so that Dr Caldwell can operate on her brain. But that's the day the base is overrun and that's when it isn't up to Miss Justineau to look after Melanie any more, it's up to Melanie to look after Miss Justineau. 
 I gave this book 5 stars but I would have given it 10 if I could - I absolutely loved it. I'm not desparately keen on stories of the undead and so on, but this is completely different to that and much more believeable (to be honest, I considered it more scary in many ways). The four main characters are really carefully thought out and well drawn and the way that they react to the circumstances feels completely believable and very likely. I did like the way that one of the characters is much less sympathetic than the others and I thought that added much to the group dynamic which may not have been there otherwise. 
 As for the story itself, it was terrifyingly believeable, almost simple in it's approach. From the beginning, there really was only one way things could go, but there is no way I would have predicted the brilliant ending although it was clearly there all along. The simplicity of the story means that it's hard to review without giving too much away so all I can say is, read it and you'll see for yourself!