The film opens with a deeply personal video journal entry from Ellie Linton, who questions herself on how to narrate their harrowing tale. Ellie decides to start from the very beginning, setting up an emotional journey that lies ahead. In the charming rural town of Wirrawee, New South Wales, she is a spirited high school student gearing up for an adventurous camping trip to a remote area called "Hell's Gate," affectionately shortened to "Hell." She's joined by her childhood friend Corrie McKenzie, along with their significant others, Kevin Holmes and Lee Takkam, and buddies Robyn Mathers and Fiona "Fi" Maxwell. Together, they embrace the thrill of adventure.
As darkness blankets the campsite, Ellie is jolted awake by an alarming sight—a sky filled with military aircraft. The sense of peace shatters, prompting the group to return to Wirrawee, only to discover their homes eerily deserted, without power, internet, or phone services. They climb a nearby hill to witness a disturbing scene: only the flickering lights of the hospital and the showground pierce the night. Arriving at the showground, they find townspeople imprisoned by an unseen foreign military force. Ellie is horrified as she witnesses an act of violence when a man is struck down by gunfire, causing her to retreat in terror. In the ensuing chaos, Lee and Robyn disappear into the shadows.
Seeking safety at Corrie's house, the group becomes silent observers of war's destructive power when an RAAF jet is tragically shot down by enemy forces. When an enemy helicopter approaches, Homer bravely shoots at it, effectively destroying its searchlight, allowing the group to escape just moments before Corrie’s home is reduced to rubble by an aerial assault.
Ellie and Homer stealthily navigate back into town, where they reunite with Robyn at her home. They discover Lee has sustained serious injuries and is being treated by the local dentist, Dr. Clements, who informs them that enemy troops are operating from ships in Cobbler's Bay, beyond Heron Bridge. After a tense encounter with armed vehicles, the four friends reconvene at Corrie's, pondering a return to Hell. On their way, they unexpectedly come across classmate Chris, blissfully unaware of the war's reality, his state of highness showcasing the stark contrast between his oblivion and their dire situation.
As feelings simmer between Ellie and Lee, their moment of tenderness is interrupted by Ellie's growing frustration with Chris, who dozes off while on guard duty, putting everyone at risk. Her anger flares as she confronts him, finger hovering near the trigger of her firearm. Fortunately, their friends step in to prevent a potentially disastrous outcome.
Seeking safety and a sense of normalcy, the group heads back to Hell, hoping it will offer sanctuary. However, Lee's attempts to discuss feelings with Ellie are met with confusion and frustration, as she storms away, leaving him troubled by their mixed signals.
Their brief serenity is shattered when they intercept a radio message revealing that Australia has been overrun by the Coalition Nations, a ruthless entity intent on plundering its resources. The group quickly realizes the magnitude of their plight as they learn that Cobbler's Bay remains one of the few ports still under enemy control. Determined to disrupt the invaders, they set their sights on destroying Heron Bridge, a key strategic point.
Under the cloak of night, Ellie and Fi undertake a daring mission to hijack a petrol tanker, positioning it strategically near the bridge. Just as they are preparing for their friends to take their positions, they are spotted by sentries, forcing them into a frantic race to maneuver the tanker. Meanwhile, Homer and Lee devise an unorthodox distraction by herding cattle to draw the guards' attention, allowing Ellie to successfully place the tanker in position. The ensuing explosion demolishes the bridge, but not before Corrie suffers serious injuries during their escape.
In the aftermath, Kevin selflessly chooses to stay with Corrie, resolving to drive her to the hospital despite the risks of capture. As they slip into an uncertain fate, Ellie crumbles under the weight of their trials, breaking down in Lee's arms as she mourns their staggering losses.
In a final show of resilience, Ellie completes her video log, affirming the group's commitment to wage their guerrilla war from Hell, declaring their unwavering resolve to fight until the invasion is thwarted and freedom is restored.
