In 2012, after deposing the dictator Gadaffi, rival local militant factions have repeatedly raided Gadaffi's armories for weapons. As a result, a deadly civil war has broken out which has made Benghazi the most dangerous place on the planet. In 2012, Benghazi, Libya is named one of the most dangerous places in the world, and countries have pulled their embassies out of the country in fear of an attack by militants. The United States, however, still has a diplomatic compound (not an official embassy) open in the city. Less than a mile away is a not-so-secret CIA outpost called "The Annex", which is protected by a team of 6 private military contractors from Global Response Staff made up of former military special operations personnel. New to the detail is Jack "Da" Silva (John Krasinski), who arrives in Benghazi and is picked up by Tyrone S. "Rone" Woods (James Dale), a member of the team and a personal friend of Silva. Arriving at the Annex, Da Silva is introduced to the rest of the team and the chief (David Costabile), who constantly gives the team strict reminders to never engage the citizens to avoid conflict with local militants in the area. The chief also believes that there is no real threat in Libya as he believes the Libyans are thankful to Americans for supporting their revolution. He is not supportive of the armed non-CIA protective detail guarding his compound, as he feels they are a threat to their security.The U.S. Ambassador to Libya J. Christopher Stevens (Matt Letscher) arrives in Benghazi to maintain diplomatic connections in the middle of the political and social chaos. Despite warnings, Ambassador Stevens decides to stay at the Special Mission with limited protection from a pair of Diplomatic Security (DS) agents and guards hired from the local February 17th Martyrs Brigade militia, nicknamed "17-Feb". On the morning of the eleventh anniversary of the September 11 attacks, Stevens notices suspicious men taking pictures of the compound and notifies his security detail. Back at the Annex, the GRS team communicates with their families and Da Silva finds out that his wife is pregnant.That night, a group of Islamist militants from Ansar Al-Sharia assault the compound. Unwilling to work as protective guards for $28 a day, the local 17-Feb guards quickly surrender their posts, allowing the attackers easy access to the Special Mission compound. This first attack happens around 9 pm. Scott Wickland (Davd Giuntoli), a Diplomatic Security agent, takes Stevens and an officer, Sean Smith (Christopher Dingli), into the safe room. Unable to breach the safe room, the attackers set the building on fire hoping to burn the men out.Wickland is able to escape but loses both Stevens and Smith. At the Annex, the GRS team desperately wants to go to the compound to help, but the chief refuses, fearing that the GRS team's departure would leave the Annex vulnerable. meanwhile the Embassy in Tripoli has no military assets to help the team in Benghazi and the African Command in Germany requires 45 mins and an approval from the white House to respond to this crisis. Refusing to listen, the GRS team dispatches to the compound and meets up with the DS agents. Silva and Woods go into the building to try to find Stevens and Smith, but are only able to find Smith, who has died from smoke inhalation. The team retreats back to the Annex. The team from the compound also follows suit, but after Wickland goes the wrong direction, they are followed back to the Annex. The cars enter the Annex at around 12 am.Knowing an attack by the militants is imminent, the staff of the CIA Annex make several desperate calls for help. The only help they can get is from Glen "Bub" Doherty (Toby Stephens), a Global Response Staff officer based in the US Embassy in Tripoli, who forms a team including two Delta operators that flies to Benghazi after several delays. Meanwhile, the GRS team fends off the militants as they try to breach the Annex perimeter late into the night at around 1 am. As the attackers regroup after failed assaults, the GRS team takes time to regroup as well, and the downtime allows them to think about their families while considering the gravity of the situation. After repelling the largest attack wave, the Annex receives word from ISR that help is in route from Croatia in form a strike package of fighter aircraft & helicopter laden with reinforcements. This is around 3 am.With the GRS team compromised, and the Annex now vulnerable, the remaining GRS operators watch as a convoy of vehicles rolls toward the Annex at 5 30 am. Fearing the worst, the operators prepare to make a final stand, until it is revealed that the convoy is an element of the Libya Shield Force militia escorting the GRS reinforcements. They also find out that Stevens was found behind the compound but was pronounced dead at the hospital from smoke inhalation. The militants launch a mortar attack at 6 am that wounds one of the DS agents and kills both Woods and Doherty. But the GRS team is able to withstand the onslaught of the militia and push them back. The promised air support never came. At 6 15 am a huge convoy of 50 vehicles rolls towards the annex. As the team preps for the final stand, they realize that this is the rescue team they have been waiting for all along. The entire annex is evacuated, and the CIA team leaves Benghazi by 8 30 am. The GRS team stays behind for their plane. As the remainder of the team wait at the airstrip with the bodies of Stevens, Smith, Woods and Doherty, they reflect on the events that happened and how they will most likely receive no recognition for defending the Annex as they were off the books. They are finally evacuated at 10 30 am. Closing titles reveal that all of the surviving members of the Annex security team received medals in a private ceremony and have since retired from the GRS team and live with their families.