Capt. Mitch Nelson (Chris Hemsworth) is the leader of a small military unit representing the first US military troops to set foot in Afghanistan after the attacks of September 9, 2001. Among those under his command are Officer Hal Spencer (Michael Shannon), sarcastic Sam Diller (Michael Pena) and Army Expert, Ben Milo (Trevante Rhodes). They in turn receive orders from Col. Mulholland (William Fichtner), a single person, and just as direct Lt. Col. Bowers (Rob Riggle).
Their mission is to enter northern Afghanistan, on the border with Uzbekistan, benefiting from the help of a Uzbek war general named Dostum (Navid Negahban), who has his own reasons to deal with the Taliban. Together with Dostum and his men, Nelson and his comrades have to take control of the Afghan city of Mazar-i-Sharif, a very important control point for the Taliban forces.
But in spite of the tremendous training the American soldiers did and their courage, the American troops did not realize that they would have to cross an extremely difficult and ruthless ground – a land known to have destroyed the centuries-old empires at row – with horses. Moreover, they will have to complete this mission within only three weeks before the frost of winter comes. Due to the fact that they will ride on horses, they are very exposed to attacks by the Taliban, having no protection, being practically safe targets.