Growing mistrust between the British, American and Iranian Governments culminates in a series of high-risk operations at home, pushing the Section to its very limits. As Iran's race to become a nuclear power impacts on British and American security, the distinction between friend and foe becomes ever more blurred. Harry and his team start to question exactly whose agenda they're working to and who they can trust - both on and off the Grid. The electric atmosphere between Adam and Ros comes to a head but things are complicated further by Adam's ongoing and dangerous affair with a key asset inside the Iranian Embassy. Harry gains a new friend ont he Grid when he recruits old MI5 colleague Connie as desk officer. Clever, and with plenty of old-school tricks up her sleeve, she might just be able to fill the void left by Ruth's departure.