The movie begins with a tense mortar attack on the 1st Australian Task Force (1 ATF) base at Nui Dat, carried out by the Viet Cong (VC) and the People's Army of Vietnam (PAVN). During this assault, Major Harry Smith, portrayed by [Travis Fimmel], remains remarkably composed under pressure, issuing commands for his troops to take cover and prepare for action. In stark contrast, some soldiers are shown disregarding the danger, amusing themselves with cards or drinking beer while the attack rages around them. The base manages to repel the mortar fire with counter-battery strikes, successfully neutralizing the enemy mortar crew.
Following the attack, Major Smith volunteers his unit, Delta Company of the 6th Battalion, Royal Australian Regiment (6 RAR), to investigate the nearby rubber plantation at Long Tân, which is about two kilometers from Nui Dat. Their goal is to locate enemy mortar positions and observe their retreat. Meanwhile, Bravo Company is tasked with finding the mortar firing points and the direction in which the VC and PAVN forces are withdrawing. When they do not encounter any enemy patrols, Bravo reports no signs of activity.
The following day, Delta Company is ordered to relieve Bravo, a move that causes them to miss a planned Australian concert featuring musicians Little Pattie and Col Joye along with the Joy Boys—a detail that underscores the everyday life and cultural moments that are overshadowed by the chaos of war. As they push forward, Delta discovers fresh tracks leading away from the mortar sites, indicating enemy movement. 11 Platoon, led by soldiers like [Seán Lynch], takes the forefront and quickly makes contact with a small VC patrol. Their patrol advances deeper into the plantation and begins to widen the gap with 10 Platoon and the rest of Delta Company.
Soon, 11 Platoon finds itself under severe attack. They call in artillery support from Nui Dat, with their fire dangerously close to their position, in an effort to hold back the advancing enemy forces. Reinforcements from 12 Platoon arrive, but the assault intensifies. 11 Platoon becomes isolated, teetering on the brink of being overrun. As the situation darkens, back at Nui Dat, Brigadier [Richard Roxburgh], played by [Richard Roxburgh], hesitates to send additional reinforcements, fearing the risk involved. He orders Delta to withdraw, but Major Smith refuses to abandon 11 Platoon, risking a showdown with the command.
In a tense turn, Major Smith's determination forces the Brigadier to send armored personnel carriers (APCs) into the line of battle, ultimately leading to a daring rescue. Meanwhile, ammunition runs low, and the soldiers face the relentless monsoon rains. Major Smith pleads with the RAAF command for helicopter resupply. The senior RAAF officer, Group Captain Pellegrini, initially refuses to risk aircraft for a hot landing zone amid the storm. However, two brave Iroquois pilots, [Frank Riley] and [Bob Grandin], volunteer to fly in under heavy fire to support Delta Company.
Thanks to this courageous support, the soldiers are resupplied and able to sustain their defense. Against overwhelming odds, Major Smith's forces manage to hold their ground until reinforcements arrive—namely, the M113 armored vehicles and infantry from Nui Dat. The arriving forces finally force the PAVN soldiers to retreat, but not without cost. During the fierce fighting, Private Paul Large, played by [Daniel Webber], is fatally shot in the head and dies instantly.
The film closes with a poignant scene of a roll call at the base, revealing the names of those killed in action, including Large. The characters reflect on their losses, and Major Smith says farewell to the fallen soldier from the helicopter as it departs, symbolizing the heavy toll of war and the sacrifices made by these young men. The story depicts not just the brutal realities of combat, but also the camaraderie, bravery, and human costs that define their experience during the Vietnam War.
