Jamie Roberts' documentary filmed over the course of two years, which takes an intimate look at the people spreading extremist fundamentalism in Britain. In 2014 Roberts filmed Islamic extremist Abu Rumaysah, who is now one of the world's most wanted men and is suspected of being the British jihadi in the latest IS execution video. This film gains extraordinary access to a new wave of extremists, including Rumaysah, who are radicalising and grooming young British Muslims, and asks whether they really have non-violent aims, as they claim, or are a genuine threat to society.