Wild's End: The Enemy Within — Dan Abnett

As survivors of the alien invasion of Lower Crowchurch try to cope with what happened to their small town, the military arrives in an attempt to cover up the "incident." Town residents are immediately detained, questioned, and treated with suspicion. Clive, Susan, and the others will need to escape imprisonment if they're to get the word out and warn the rest of the world before the aliens return. Collects the complete limited series.