The near future. Scotland has been left devastated by a plague that has swept the country. The scattered population struggle to survive from day to day. And the blame for this pandemic falls squarely on 'witches' - seemingly ordinary people with extra-ordinary powers - who are hunted down and forced to stand trial by government sanctioned witch-hunters. Thomas Mackie is one such witch-hunter and, alongside his dog Dex, he hunts down witches in order to save enough money and buy his way to a better life, far from the poverty and devastation. But things take an unexpected turn...