The episode begins on the eve of the 2003 invasion of Iraq, where a British Army Special Forces unit take part in an operation to release a hostage. During the operation, John Porter (Richard Armitage) confronts a boy wearing a suicide vest, which he disarms. After the hostage is found, two soldiers are killed, one is left in a vegetative state, and Porter and his best friend Hugh Collinson (Andrew Lincoln) are injured. After the operation, Porter resign, but has difficulty getting another profession, eventually landing himself the role of a security guard, while Collinson becomes a high position member in Section 20 of MI6. Seven years later, British Journalist Katie Dartmouth (Orla Brady) is kidnapped outside Basra by the "Sword of Islam"; the kidnappers demand the release of one of their comrades from Belmarsh. Upon realising one of the kidnappers is the same boy as the one Porter disarmed, nicknamed "scarface", Collinson decides to "reactivate" Porter. By the time he arrives in Basra, a separate unit is tasked with retrieving Dartmouth after tracking the live feed. Unfortunately, the building is rigged with explosives and detonates, killing the unit. In the end, Porter goes on his own to the same apartment complex during the same operation seven years previous.