S2, E1: DCI RACHEL CAREY (Holliday Grainger) is living a lonely, paranoid existence, struggling with thwarted ambitions while seconded to Counter Terrorism Command's 'mapping' department. She's officially joined the highly classified 'Correction' team, but has yet to be truly 'let in'. When her former colleagues DS FLYNN and DI LATIF bring the case of a man murdered by invisible assailants to her attention, the stakes quickly become deadly. Carey's investigation brings her into the orbit of hotshot politician ISAAC TURNER MP (Paapa Essiedu) as the case's links to national and international security start to emerge. Something is very wrong, but can she work out what before Britain's security is irrevocably compromised? And which of her colleagues can she trust?