In the northern desert of Kuwait, First Recon Marines prepare to invade Iraq as the "tip of the spear" for Operation Iraqi Freedom. At the Camp Mathilda staging ground, soldiers in First Recon's Bravo Company combat boredom, cramped tents, a lack of Humvee supplies, mustache protocol, officer ineptitude, a wind storm, an espresso machine fire, and rumors of J-Lo's death while awaiting orders from Col. Stephen "Godfather" Ferrando, the raspy-throated Commander of First Recon. They also welcome a writer ("Scribe") from Rolling Stone magazine, who'll be embedded with Bravo's five-vehicle Platoon 2 unit, riding in a Humvee with Team Leader Brad "Iceman" Colbert, driver Ray Person, and Lance Cpl. Harold Trombley. After an unexpected (and portentous) mass delivery of pizza, the soldiers finally break camp, pack up their Humvees, and cross the northern border into Iraq--and an uncertain future.
Under orders to consider any Iraqi carrying a weapon hostile, Bravo busts north towards Nasiriyah. Prompted by an anxious Major General Mattis, Ferrando orders Bravo to cross the Euphrates the next night, but they end up entering Nasiriyah by day, driving through the city with minimal gunfire, save for an AK-47 assault by Platoon 3 leader "Captain America" McGraw on an empty car. Heading north to Mesopotamia, Bravo continues to lag behind other companies, partly because of a wrong turn. Chomping at the bit while others are carrying the fight, the platoon finally gets "lit up" in a violent but successful skirmish in Al Gharraf, during which Trombley scores his first kill. Elated and relatively unscathed, the platoon celebrates its triumph.
Having survived its first trial by fire, Bravo presses forward, awaiting orders for a new recon mission. Scoping out a roadside hamlet, the company watches in horror and disbelief as a regimental combat team arrives with guns firing and the hamlet is obliterated. On new orders, Bravo heads to the town of Ar Rifa, where Fick tries to take control of a dangerous situation created by Encino Man, who requests an artillery strike on a phantom RPG team. After Alpha Company shells the town, Ferrando issues a new, more urgent order: push ahead 40 kilometers and capture an airstrip controlled by Iraqi's Republican Guard and defended by tanks. Widescreen.
Having raced to capture the airfield, First Recon is now miles ahead of the rest of the American force and has some time to rest and regroup. The abandoned supply truck has been looted and destroyed and the company is now down to one meal a day. After expressing their dismay to their commander, Alpha is tasked with a different mission: to recover the body of a captured Marine who was murdered in Ah Shatra, which takes a twist when a CIA-trained army of Iraqi Freedom Fighters arrives and then just as quickly departs. Meanwhile, Bravo pushes north, clearing hamlets and facing heavy fire. Along the way, Trombley is able to redeem himself, at least a bit in the eyes of his fellow Marines. As Alpha heads into Ah Shatra, Bravo sets up a roadblock outside of Al Hayy. The men debate the proper protocol to stop cars, but it's a fine line between being cautious and putting oneself at risk. Bravo steps off as Alpha returns to the fold, having raised more questions with their mission in Ah Shatra than they answered.
As they scope a tiny hamlet, the men of Bravo are frustrated by the capricious nature of the war, and Colbert struggles to defend the actions of the higher-ups. First Recon finally gets a chance to use their skills and exploit some intelligence from Iraqi locals about an ambush at a bridge ahead. For once, First Recon isn't tasked with heading straight into the ambush, but instead gets to rest and watch as better armed LAVs assault the bridge. With the ambush thought to be quelled, Colbert's team is ordered to lead Bravo across the bridge. They quickly discover that the enemy combatants still have some fight in them, but led by Colbert, they manage to escape almost unscathed. After regrouping, Bravo is ordered to cross the bridge again, this time with Bravo 3 in the lead, and again hits a snag. The following morning, First Recon examines the bodies of the men they fought the night before, and discover their enemy is not who they imagined. Bravo continues north to Al Muwafaqiyah, where they are tasked with setting up another roadblock and with destroying the Republican Guard outpost, which, unfortunately, is in the town's only school. Despite Colbert's exhortations to the men to hold their fire unless its absolutely necessary, Bravo has an incident at the road block. As they again head north, the inexactitude of the war weighs heavily on the men.
Outside of Al Kut, Captain America is over-eager in his attempts to subdue a prisoner, while his men's growing disillusionment with his command is growing more apparent. Meanwhile, Ferrando relays to his officers the news that his counterpart in the Regimental Combat Team has been relieved of duty despite achieving his objective. Encino Man takes Ferrando's speech to heart and puts Fick on notice that there will be no more questioning of his orders. First Recon's next mission is to escort civilians fleeing from Baghdad down the highway. The men are overcome by the humanity and try to help, which gives Fick pause. Colbert and the others realize that with Baghdad being the next stop for the American forces, their war has probably come to an end, which rankles Ferrando, who itches to get back in the game. After reuniting with an old friend who tells horror stories about the Marine reservists, First Recon heads to Baqubah, a town north of Baghdad, to go up against Iraqi armor--with those same reservists in tow. Despite some mishaps along the way, the mission is successful, and the Marines take some prisoners. Unfortunately, Sgt. Eric Kocher, Colbert's counterpart in Bravo 3, and one of his men are accused by a reservist of mistreating a prisoner. First Recon heads back to Baghdad, unsure of what their role will be in the city.
Bravo reaches Baghdad, where the men are shocked by the sheer size and scope of the city. They set up shop in an abandoned cigarette factory and get a chance to rest for a bit, although the factory grounds aren't quite as secure as they'd like. Hampered by having only one translator for the battalion, First Recon can only send out sporadic patrols into the city. During those patrols they discover the list of problems the Iraqis face is much greater than the Marines could imagine. Their attempts to help are thwarted by ever-changing assignments, a lack of necessary supplies, unruly locals and cultural misunderstandings. While Colbert worries about his friend Kocher, who has been demoted, Fick becomes more and more disillusioned with the lack of a plan in Baghdad, and refuses an order that would put his men in danger. The men learn their final night in Baghdad is upon them and celebrate in a soccer stadium. They head south to an abandoned Iraqi army base to wrap things up, but not before Ferrando's misguided enthusiasm has disastrous results. The Marines take inventory and reflect on their time in Iraq, and tensions that have been simmering throughout finally boil over during a friendly football game. Scribe says his goodbyes to the men and has an interesting conversation with Ferrando before heading off. One of the Recon Marines shows the movie he's put together from footage he's shot. The men enjoy the sights and sounds before drifting off.