It's Christmas Eve, and Jodie (Linzey Cocker) has come home for the holiday only to find her estranged mother, Beth (Neve McIntosh), in the throws of passion with a stranger. After Jodie takes off to a friend's house across the street, Beth is left feeling shame and anguish with a man she hardly knows -- but soon her world is turned completely upside down when military personnel storm the neighborhood and hold people inside their homes at gunpoint. It's unclear if this is a terrorist attack or worse, but when bodies start piling up, Beth and the remaining survivors are faced with a monstrosity that seems to overwhelm any hope of survival. Will Beth make it outside to save her daughter? Will either live through this ordeal?