Episode 1 (Season 1)

Still haunted by the memory of a disastrous Special Forces mission which he led in 2003, John Porter is given an opportunity to redeem himself by returning to Iraq to rescue a kidnapped TV reporter.

Summary
On the eve of the 2003 invasion of Iraq, a Special Forces unit takes part in an operation to release a hostage, during which, John Porter (Armitage) disarms a boy named As'ad wearing a suicide vest.

After the hostage is found, two soldiers are killed and one is left in a vegetative state. Believing the boy was responsible, and that Porter did not kill him, he is dishonorably discharged. Fellow officer Hugh Collinson (Lincoln) becomes the head of Section 20 of MI6.

Seven years later, journalist Katie Dartmouth (Brady) is kidnapped outside Basra by the "Sword of Islam"; the kidnappers demand the release of one of their comrades from Belmarsh Prison. Upon realising one of the kidnappers is As'ad, Collinson "reactivates" Porter.

A separate unit is tasked with retrieving Dartmouth after tracking the live feed, but are killed when the building rigged with explosives detonate. In the end, Porter goes on his own to the same apartment building during the same operation seven years previous.