Alexander Blackman, a Royal Marine sergeant, was convicted and jailed for life for shooting an injured Afghan insurgent on the front line. Some condemn him as a war criminal, while others claim he is a casualty of war. The nation is divided. Now the shamed marine, dismissed with disgrace from the Royal Marines, is launching an appeal from his prison cell - not only against the sentence but the murder conviction itself. Blackman is the first British serviceman to be found guilty of murder during combat since WWII. This one-off documentary, made by award-winning filmmaker Chris Terrill, who has himself witnessed the horrors of the Afghan conflict looks into Blackman's case. Terrill asks questions about the ethics of combat and rules of engagement in war and the mind-bending nature of active duty on the front line. As well as an exclusive interview with Blackman's wife Claire, Terrill speaks to those that condemn Blackman's actions and those that condone them, those that revile him as a killer and even those that revere him as a hero.