Ahmad Shah, a local Taliban warlord in the Korangal Valley is identified as the person responsible for the deaths of several Marines, plus any villagers who are believed to have aided the American forces in Afghanistan. A Navy SEAL team, consisting of Michael Murphy, Matthew Axelson, Danny Dietz and Marcus Luttrell, is ordered to capture Shah.
Inserted overnight via helicopter, the four-man team make their way toward Shah’s last known location. Due to the mountainous terrain the team are operating in, communications with J-Bad become difficult. Though the team identify Shah, they are discovered by local villagers; one of whom is carrying a walkie-talkie. Believing that the villagers are Taliban sympathisers, the SEALs debate setting them free or killing them. Murphy orders them to be set free.
The team proceed up the mountainside, aborting their mission and intend to extract. However, true to the SEALs’ concerns the villagers alert the Taliban, who pursue the team. Though the SEALs begin with the advantage, the sheer number of the Taliban forces begins to overwhelm them and their position. Pushed toward a ravine the SEALs are given little choice but to jump, but are thrown off balance when an RPG detonates in front of them. Dietz is killed and the remaining SEALs try desperately to raise support. Murphy scales the cliff to gain a clear signal which finally alerts the QRF, though he is killed shortly after.
The QRF scrambles to the SEALs’ aid, though the two Chinook helicopters fly in without Apache support. Briefly encouraged by the arrival of reinforcements, Luttrell and Axelson watch helplessly as one Chinook is shot down by an RPG. The second aborts, leaving Luttrell and Axelson to fend for themselves. Already grievously wounded from battle, the disoriented Axelson is soon cornered by Taliban gunmen and killed. Luttrell is also discovered, though he survives an RPG attack and is able to hide from his pursuers overnight and escapes.
Wandering alone, Luttrell happens across a small stream when he is discovered by Mohammed Gulab, a local Pashtun. Taking the wounded and exhausted Luttrell into his care, Gulab hides him from the Taliban in his home, and also sends another villager to the nearest American base to report on Luttrell’s location. Shah arrives at the village to execute Luttrell, however the villagers resist. Shah leaves, but returns later with several Taliban gunmen and engage the villagers. Rangers arrive mid battle and evacuate Luttrell, who also thanks Mohammed for his assistance.
Images of the real Luttrell, Gulab and the fallen service members killed during the mission are shown during a four-minute montage, and an epilogue explains that the Pashtun villagers agreed to help Luttrell as part of a traditional code of honor known as the Pashtunwali.