Iraqi General Mohammed Al-Rawi (Yigal Naor), hiding in Baghdad, is meeting with his aides talking about the invasion of Iraq early in the morning of March 19th, 2003. Al-Rawi suggests that they wait until the Americans arrive and perhaps make his army an offer to join their forces.

Four weeks later, Chief Warrant Officer Roy Miller (Matt Damon) and his squad investigate a warehouse, believed to be holding Weapons of Mass Destruction. To Miller's surprise the warehouse is not secure with looters making their way in and out as soldiers from the 101st Airborne Division sporadically fight the Iraqis. But they find that the warehouse is empty. At a debriefing, Miller brings up the point that the majority of the intel given to him is inaccurate and anonymous, stating that on his last three attempts to find WMDs, his team had come up with nothing. High-ranking officials quickly dismiss Miller's theory about the intelligence being false. After the debriefing, Miller meets Martin Brown (Brendan Gleeson), a CIA officer based in the Middle East who tells Miller that the next place he is going to investigate for WMDs is also empty, as a UN team had already searched there two months ago.

Meanwhile, Clark Poundstone (Greg Kinnear) is welcoming Ahmed Zubaidi (Raad Rawi) an Iraqi politician at Baghdad International Airport, where he is interrogated by Wall Street Journal correspondent Lawrie Dayne (Amy Ryan). She asks if she could speak to "Magellan," to which Poundstone says that he is heavily "locked up."

While investigating another site, Miller is approached by the Iraqi who calls himself "Freddie" (Khalid Abdalla), who tells Miller that he saw some Ba'thist VIPs meeting in a nearby house. Miller and his men swiftly burst into the house. Al-Rawi narrowly escapes, but one of his henchmen is taken into custody. Before Miller can extract any more information, the man is taken by special forces, sent by Poundstone.

Miller goes to Brown's hotel in the green zone and tells him what happened. Brown gets permission for Miller to visit the man taken by special forces. Before leaving, he is approached by Dayne. Miller soon finds the Iraqi informant in prison. Now severely wounded, the man responds to Miller's question with one word: "Jordan". With Brown's help, Miller's suspicions are confirmed that Al-Rawi met with Poundstone in February in Jordan as Poundstone's inside man.

Miller has by now realised that Poundstone probably wants to prevent Al-Rawi disclosing the fact that he had confirmed no WMDs. When Miller tries to meet with Al-Rawi to encourage him to turn himself in before he is killed by Poundstone's men, he is kidnapped by Al-Rawi's men because Poundstone announced the decision to disband the entire Iraqi army. Al-Rawi tells Miller that he told Poundstone there had been no WMD program since the First Persian Gulf War; Poundstone apparently lied to his superiors in Washington so that Iraq would be invaded. American forces commence an attack on Al-Rawi's positions, and the general flees. Meanwhile, Miller kills his captor and races to capture Al-Rawi. When he finally manages to catch up with him, Freddie suddenly appears and kills Al-Rawi, saying to Miller, "It is not for you to decide what happens here." Later in his hotel room, Miller writes a report of everything that happened.

Miller confronts Poundstone in a meeting and gives him the report. Poundstone tells Miller that WMDs do not matter. Then Miller violently grabs Poundstone, saying "the reason we go to war always matters," but they are broken up. Poundstone then rejoins the Iraqi meeting, only to see the Iraqi factional leaders yelling at each other and leaving the meeting. Afterwards, Dayne receives an e-mailed copy of Miller's report. Miller sent it to all major news agencies around the world. The camera then pans out to show Miller and his squad driving off on the Iraqi highway, which is now used by Coalition vehicles, with the Iraqi oil fields in the background.

Source: imdb.com