This opening part of the series tells the story of a close-knit group of friends from 3 Platoon, 1st Battalion Royal Anglian regiment, who were sent to Helmand province in 2007. For most of them it was their first experience of war. The whole tour was filmed on a helmet camera by the platoon's sergeant, who captured the moment when one of his men, 19-year-old Private Chris Gray, was killed in a Taliban ambush. The film explores the effects of his death on both his mates in the platoon and his family back in the UK.

The second episode focuses on a young platoon from the Grenadier Guards and their terrifying struggle with landmines, also known as Improvised Explosive Devices (IEDs). Captain Alex Rawlins filmed his men as they lost of one their mates, 23-year-old Guardsman Jamie Janes, who stood on a landmine during a patrol. The film shows how Jamie Janes's death became a turning point in the British public's awareness of the human cost of IEDs and how a misspelled letter turned into a political storm for the then prime minister, Gordon Brown.

The final part starts in 2009 and tells the story of 2nd Battalion Princess of Wales regiment as it comes to terms with new rules of fighting brought in to protect civilians. Private Mike McCabe is filmed being shot in the leg during a Taliban ambush. By 2010, the Scots Guards find themselves fighting a very different war - a battle for hearts and minds. They struggle to train a local force, the Afghan National Police, who fight in a reckless and dangerous way. The risks are hammered home when Guardsman Daniel Clarke films a three-year-old girl who has been seriously injured by a rocket-propelled grenade fired by the ANP. The Scots Guards tour ends in tragedy when six members of the ANP are massacred in their sleep.