With the UK terror threat level at "severe", the drama-documentary episode based on real-life stories focuses from inside the UK’s counter terrorism unit. It tells the incident of an ISIS-inspired terrorist group planning a firearms attack, and follows with the ongoing police investigation. The story follows with Joseph, a young man who, while in prison on drugs charges, is recruited and radicalised by an Islamic extremist. Through drama and interviews, it also reveals how UK agencies are working to keep the public safe from what experts fear is the most likely scenario for a UK next major terror attack.