Set in the UK in the immediate aftermath of a mysterious illness which swept the country and left millions dead, the series follows the trials facing a reluctant hero, Dan, and the group he forms around him. They must battle the elements, find sufficient supplies and equipment to survive, and protect themselves against the most destructive force on the planet: other people. The survivors have established a home, but they still have to face the brutality of human nature. Not only do they have to survive, they must keep their humanity.