The story unfolds through the reflective memories of Max Eriksson, a seasoned Vietnam veteran grappling with the ghosts of his past. In a haunting flashback, we accompany Lieutenant John C. Reilly as he leads a group of American soldiers on a dangerous nighttime patrol. Their mission goes awry when an anxious comrade inadvertently exposes their location to the Viet Cong (VC). In the chaos that ensues, Sergeant Tony Meserve, portrayed by Ving Rhames, heroically saves Eriksson from a collapsing tunnel. The platoon regroups by a serene river village in the Central Highlands, where light-hearted banter temporarily shields them from the looming horrors of war.
Tragically, their brief moment of peace is abruptly disrupted by the discovery of Specialist 4 "Brownie" Brown's lifeless body, a grim victim of an unexpected VC ambush. This severe loss weighs heavily on Meserve, echoing throughout the platoon. Shortly after, Private First Class Antonio Dìaz arrives to fill the void left by a fallen comrade, bringing a fresh perspective into the squad's dynamics.
As the days progress, Eriksson's pent-up frustration concerning the squad's ongoing leave denial begins to fester, leading him to express concerns that are largely ignored. Meserve, alongside Corporal Thomas E. Clark and Private First Class Herbert Hatcher, concocts a plan to abduct a Vietnamese girl named Tran Thi Oanh, disregarding Eriksson's entreaties for discretion. This reckless nocturnal expedition marks the beginning of a profound moral quandary that will haunt the men.
Days into their tortured existence, Dìaz starts to grapple with his conscience concerning the escalating violence, ultimately seeking Eriksson's counsel to resist the pressure perpetuated by the platoon. However, his resolve is put to the test when Meserve's tyrannical grip forces Eriksson to assume a guard role outside a dilapidated structure while the others engage in horrific acts against Tran. Eriksson's internal struggle escalates as he wrestles with the stark contrast between humanity and the brutal realities of combat.
As dawn breaks, Eriksson is burdened with the duty of guarding Tran while the squad sets its sights on a crucial railroad bridge that overlooks a strategically vital Viet Cong supply depot. Through simple acts of kindness, Eriksson gradually earns Tran's trust, secretly planning an escape to return her to her family. Just when it seems hope may return, Meserve sends Clark to retrieve them, crushing Eriksson's aspirations for salvation. The narrative races toward its climax as Eriksson finds himself increasingly ensnared in the web of chaos and despair.
In a devastating turn of events, Meserve orders Dìaz to call in air support for an attack on the depot and chillingly commands the execution of Tran. Before the execution can commence, Eriksson rebels, firing his rifle into the air and inadvertently revealing their position to the nearby VC. In the ensuing firefight, Tran attempts to flee, enduring brutal attacks from Clark. Eriksson's desperate effort to save her is cut short when Meserve mercilessly strikes him down. Helpless, he watches as his entire squad fires upon Tran, who ultimately succumbs to her injuries, falling from the bridge to her tragic demise.
After this harrowing ordeal, Eriksson finds himself recovering in a makeshift military hospital, where he recounts the harrowing events to Rowan. Rowan encourages him to seek guidance from John C. Reilly and Captain Hill, the company commander. Both men, however, prefer to ignore the incident until Eriksson’s unwavering quest for the truth ignites Hill's fury. Determined to silence Eriksson, Hill conspires to transfer him to a tunnel rat unit alongside Meserve's squad.
In a tense turn of events, Eriksson narrowly survives an assassination attempt from Clark while in the latrine, forcing him to confront the reality of their actions. Driven by anger and defiance, Eriksson storms a tent to confront Meserve, reminding him that eliminating him would change nothing, as no one cares about their vile acts. Meserve, taken aback, dismisses Eriksson's concerns, but the confrontation marks a pivotal moment in Eriksson's struggle.
With nowhere else to turn, Eriksson confides in an Army chaplain, recounting the dreadful patrol. The chaplain’s report triggers an investigation that culminates in the court-martial of the squad members. Meserve is sentenced to 10 years of hard labor, while Clark faces life imprisonment, and Hatcher and Dìaz receive 15 and 8 years, respectively.
As the film closes, Eriksson awakens from a distressing nightmare on a J-Church transit line in San Francisco, sitting close to a Vietnamese-American student who bears an uncanny resemblance to Tran. When she gets off at Dolores Park, she leaves behind a scarf, prompting Eriksson to chase after her to return it. Their brief exchange leaves Eriksson with a poignant sense that justice has been served, as she unknowingly stirs memories of a haunting past.
