*CUT TO THE CHASE*
NOTE: This spoiler was submitted by Jeremy
The film starts with news reports on previous attacks on U.S. soil initiated by terrorist leader Osama Bin Laden. Cut to September 11, 2001 - Mitch Nelson (Chris Hemsworth) is with his wife Jean (Elsa Pataky) and daughter Maddy (Marie Wagenmen) when he sees footage of hijacked planes striking the World Trade Center. Elsewhere in Kentucky, Nelson's fellow soldiers are learning of the news as well.
Nelson goes to his commanding officer, Lt. Colonel Max Bowers (Rob Riggle) to request a leave to head to Afghanistan with his team, but since Nelson just returned from active duty in Kuwait, and the team's Warrant Officer just filed his retirement papers, Bowers refuses to let him go. The Warrant Officer, Hal Spencer (Michael Shannon), talks to Nelson before going to Bowers and ripping up his retirement papers, saying he team is more than qualified to handle the mission. Thus, Nelson resumes his position as captain of the team.
Nelson tells Jean about the mission, and she worries about him going back out there and possibly not coming back. Likewise, Spencer says goodbye to his wife and son, while their comrade Sam Diller (Michael Pena) is incentivized by his wife to come back since she won't give him any last minute sex before he must depart.
The three soldiers, plus nine other men - Ben Milo (Trevante Rhodes), Sean Coffers (Geoff Stults), Vern Michaels (Thad Luckinbill), Fred Falls (Austin Stowell), Scott Black (Ben O'Toole), Pat Essex (Austin Hebert), Kenny Jackson (Kenneth Miller), Bill Bennett (Kenny Sheard), and Charles Jones (Jack Kesy) - meet with Bowers and Colonel John Mulholland (William Fichtner) to debrief the team (dubbed Task Force Dagger) on their mission. They are to meet with an Afghan warlord with the Northern Alliance, General Abdul Rachid Dostum (Navid Negahban), to take the city of Mazar-i-Sharif in order to stop the Taliban from spreading their forces around the land and to cripple Bin Laden. The plan is to take out the Taliban with air strikes.
The team is sent off to fly to Afghanistan where they are taken to a camp site by friendlies initially mistaken to be the enemy. The men meet with a CIA operative who tells them about the ongoing feud between some of the generals in the area fighting against the Taliban.
In the morning, the team is met by Dostum and his men. The team offers Dostum horse feed and vodka as gifts. Nelson sits and talks to Dostum to get him on their side, as well as making sure the two men have an understanding over how they will handle the Taliban.
The Taliban are seen attacking a school for having a woman teach children. Their leader, Mullah Razzan (Numan Acar), scares the young students before executing the teacher to make an example of her.
Nelson and Dostum spot the Taliban moving from a distance. They try to work out how they will initiate the air strikes, but Dostum wants to be careful since the U.S. government can pull out if they lose even one American soldier. Nelson soon calls in the air strikes, but they miss most of the enemies. The soldiers then fight back against the Taliban once they start shooting at them. Several men on the Taliban side are killed, but the TFD team are safe.
The next move is to go through the Tiangi Gap to try and catch up to the Taliban. En route, the team is attacked by the Taliban. During the battle, Nelson notices tanks from Dostum's men heading in, despite Nelson never being told about Dostum having tanks. After the fight, Nelson confronts Dostum over withholding this type of information since it could have risked lives. Nelson accuses Dostum of just being another warlord.
After coming together on a better plan, Nelson has some of his men meet up with a team from one of the rival warlords as they plan to set several soldiers among the flanks to get to Razzan before he and his men reach Mazar. Dostum doesn't like the idea at first, but Nelson convinces him it's the best plan they've got.
The soldiers initiate their attack against the Taliban, with air strikes coming down, and soldiers riding horses into battle. Many Taliban members are blown up or shot to death. Razzan attempts to get away in a van, but he crashes and is left with nowhere to go as Dostum corners him and puts a bullet in his head.
The soldiers head toward Mazar, though only Dostum and his men head in, as Nelson and his men have done their part. The two leaders part on good terms, having come to respect and trust one another. Eventually, the Taliban surrender to Dostum and lay down their weapons. Nelson and his men go home.
The last scene shows Nelson back at home with Jean and Maddie.
The final text states that against all odds, all members of Task Force Dagger survived their mission and made it home. The mission to take Mazar-i-Sharif was believed to take two years, but they did it in three weeks. Al Qaeda considers this their worst defeat. Due to the classified nature of the mission, the men involved returned to their lives without public recognition. In 2014, General Dostum became Vice President of Afghanistan, and he remains close friends with Mitch Nelson. We see a picture of a statue at the World Trade Center dedicated to the Horse Soldiers, as well as a picture of the real team.