Caught in the crossfires of civil war, CIA operatives must send a former U.S. diplomat to negotiate for the life of a friend he left behind.
Mason Skiles had a great life as a diplomat in Beirut. He and his wife, Nadia, live in a beautiful house and have been mentoring a thirteen year-old Palestinian boy named Karim. The opening scene is a party that the Stiles are hosting for other dignitaries. Karim is helping out serving the guests. When a CIA friend of Mason, Cal, comes to the party he is interested only in taking Karim in for questioning about an older brother Mason doesn't know about. What happens that night changes Mason's life forever, along several others at the party...
In 1972, Mason Skiles is a U.S. diplomat in Lebanon living in Beirut with his Lebanese wife, Nadia. They have recently begun caring for Karim, a 13-year-old Palestinian boy who claims he is without a family. While hosting a party, Skiles is confronted by his friend, CIA officer Cal Riley, who wishes to question Karim, whose brother has been linked to the 1972 Munich massacre. The party is attacked by Karim's brother, Rami, who abducts Karim; in the ensuing gunfight, Nadia is killed. Ten years later, Skiles has become an alcoholic and is working as a self-employed labor arbitrator in New England. While arbitrating a labor issue between particularly intransigent parties and struggling to keep his small firm afloat, he is approached by Sully, an old client, on behalf of the U.S. government..
In 1972, Mason Skiles (Jon Hamm) is a U.S. diplomat in Lebanon and lives in Beirut with his Lebanese wife, Nadia (Leila Bekhti), and has recently begun caring for Karim (Idir Chender), a 13-year-old Palestinian boy who claims he is without a family. While hosting a party, Skiles is confronted by his friend, CIA officer Cal Riley (Mark Pellegrino), who wishes to question Karim, whose brother Rafid Abu Rajal has been linked to the 1972 Munich massacre. Riley says that Karim was photographed with Rafid 6 months ago in Beirut and that CIA officials are at the part to arrest Karim. Skiles says that Karim is now part of the family and refuses to hand Karim over.The party is attacked by Karim's brother, Rafid (Hicham Ouraqa), who abducts Karim; in the ensuing gunfight, Nadia is killed. Riley shot at the attacker who was holding Nadia hostage, and while dying he shoots his automatic machine gun indiscriminately, and one of the bullets hits Nadia.
Ten years later, Skiles has become an alcoholic and is working as a self-employed labor arbitrator in New England. While arbitrating a labor issue between particularly intransigent parties and struggling to keep his small firm afloat, he is approached by Sully (Douglas Hodge), an old client, on behalf of the U.S. government.
Sully tells Skiles that he has been requested for an academic lecture in Lebanon, and hands him money, a plane ticket, and a passport. Skiles is initially resistant but decides to travel to Beirut. He meets several State Department officials, Donald Gaines (Dean Norris), Gary Ruzak (Shea Whigham), and Frank Shalen (Larry Pine), along with CIA officer Sandy Crowder (Rosamund Pike) (a CIA field agent working undercover at the American embassy).
Skiles is shocked at the state of Beirut as the city is half bombed out and in ruins. He is picked up by the academic team in Beirut and driven to his hotel. Crowder approaches Skiles at the hotel bar and takes him to a meeting with Frank, Gaines and Ruzak. Skiles learns that Cal Riley was recently abducted in Lebanon, and his kidnappers requested Skiles to negotiate his release. Skiles is shocked at the real reason he has been summoned to Beirut but agrees to the mission as he wants to save Riley.
On the way back Skiles makes Crowder to take him to his old mansion in Beirut, which was bombed out by Israel, after PLO had set up a transmitting station inside it.
The group meets with the kidnappers, where they learn that Karim is leading the organization. Karim demands the release of his brother in exchange for Riley, despite the Americans' protest that they do not have Rafid in captivity. Skiles suspects that Israel is holding Rafid, and travels with Ruzak to secure his release for the exchange. The Israelis reveal that they do not have Rafid, and Skiles returns to Beirut to meet with Alice (Kate Fleetwood), Riley's wife. Alice holds Skiles responsible for Riley's abduction, as she believes that he has remained in Lebanon over the guilt he feels for Nadia's death.
Roni Niv (Alon Abutbul) meets Gary in secret and confirms that Israel doesn't have Rafid in captivity. He wants Gary to publish the news of Cal's death and allow Israel to invade Lebanon to clear the place out of the PLO and other Islamist factions. Gary is skeptical of Israel & Mossad's motives and doesn't want to give up on Cal too easily.
The next day, Skiles is giving the lecture that was his official reason to travel to Beirut when a car bomb is set off outside the building. In the ensuing chaos, Skiles is instructed to leave to meet Karim. Karim brings him to Riley, who covertly tells Skiles that the Palestine Liberation Organization (PLO) is holding Rafid, and that Gaines is not to be trusted. Before releasing Skiles, Karim gives him an ultimatum for later the same night to return Rafid, or he will sell Riley to Iran.
Skiles returns to Riley's apartment to search for clues, where he encounters Crowder. She reveals that Gaines had been stealing money from the embassy, and that Riley had been preparing to make a report shortly before his disappearance. Skiles now understands that Gaines knew about Cal's knowledge of his theft and hence has every reason that Cal is never released and dies in custody of Karim. Meanwhile Gary wants Israel to attack Lebanon so that Beirut can be cleaned off in one go. So he wants Cal to die in custody and that gives US every reason to step out of Israel's way to invade Lebanon.Skiles convinces Crowder that the PLO is holding Rafid, and she steals $4 million from the CIA office to trade for Rafid.
Crowder and Skiles lead an attack on a PLO officer in order to force a trade for Rafid. After a payoff to his PLO captors, they bring him to the exchange with Karim, crashing through a Christian militia checkpoint on the way. Skiles curses Rafid for his past deeds killing innocent people before walking out to negotiate with Karim, staying until his friend Riley is safely back with Crowder. Rafid and Karim are united.
As Skiles starts to head back to the van, Rafid sees him and is enraged over Skiles's previous words, and tries to kill him before he is shot and killed by a sniper. The Americans successfully escape, and the audience sees the sniper is actually Bernard. Bernard escapes with Sandrine, the mistress of the PLO officer whom Skiles attacked, who is also an Israeli agent.
Before departing Beirut, Skiles learns that Gaines has unexpectedly retired and that Ruzak has left Beirut. Crowder announces her intention to apply for the newly vacant station chief job, and Skiles offers his services as a negotiator.
News footage is shown of the subsequent 1982 Israeli invasion of Lebanon, increasing international involvement in the country, and, finally, the 1983 bombings of the U.S. Embassy and the U.S. Marine Corps' barracks. This signals the rise of greater American involvement in Lebanon and the wider Middle East.