A bomb explodes in a busy souk, causing massive devastation. A gunman walks into a mosque and starts shooting. But this isn't the Middle East, this is Cardiff . . . With the city on high alert and all officers being drafted in to aid the search for the attacker, DC Will MacReady feels sidelined when he's asked to investigate a knife attack on a young woman. Still trying to prove himself after the events of the previous year, which left his sergeant injured, and still coming to terms with events in his personal life, MacReady wonders if he's even cut out for the job. However, when his case appears to offer a lead to the attacks, MacReady must put everything on the line in order to do what is right. Can he prove to everyone, as well as to himself, that he has what it takes to be a good copper?