It's 2003 and a month after the U.S. military invasion of Iraq to overthrow Saddam Hussein. Army Chief Warrant Officer Roy Miller (MATT DAMON) is in charge of a team assigned to find the Weapons of Mass Destruction (WMD) that reportedly necessitated the attack and current occupation. The only problem is that every site they're sent to turns up empty, and Miller wants to know why they're getting bad intel.
Compounding the issue is that few of his superiors want to hear about any of that, especially Pentagon official Clark Poundstone (GREG KINNEAR) who's in country to coordinate bringing democracy to Iraq. But CIA agent Martin Brown (BRENDAN GLEESON), who disagrees with Clark's game plan and thus clashes with him about the right way to proceed, confirms Miller's suspicions that something isn't right.
Things become more complicated when Miller and his team encounter "Freddy" (KHALID ABDALLA), a local Iraqi who claims he's seen the gathering of a clandestine meeting of Hussein's Baathist supporters, that turns out to include General Al Rawi (IGAL NAOR). Miller realizes if he can get his hands on the general, he can uncover the truth about the WMD program. Thus, with Freddy now in tow as his translator, Miller and his team raid the meeting.
Al Rawi escapes, but Miller thinks he's found something in the form of a highly coveted book one of the meeting attendees possesses. Just then, however, Special Forces Lt. Col. Briggs (JASON ISAACS) -- who's working directly for Poundstone -- swoops in and takes that man, but doesn't get the book. As Miller digs deeper into that and eventually meets Wall Street Journal reporter Lawrie Dayne (AMY RYAN) -- who's been writing extensively about WMD -- he soon realizes he's stumbled upon a cover-up of epic proportions.
Working under the guidance of Brown, Miller then races against time to find Al Rawi and discover what he knows, all as Poundstone sends Briggs to kill the General and his followers before any of their information can get out.