The characters in the first book ran and hid from zombies. They met a some more characters in the second book who were running and hiding, and together they ran and hid. Purification (mis-labelled the last in the trilogy) offers little in the way of conclusion either. In fact the content is still composed of running and hiding, rinse and repeat. There is little in the way of character development from the survivors, a clear division exists between runners and fodder. That all said, Purification doesn't set out to be different, it's niche in the genre is to fulfil a bleak zombie-infested Britain and it does just that. Straight-forward and unsurprising Purification is an easy time-filler and stays true to the two previous entries.