Eight contestants embark on a thrilling journey to Perth to participate in an internet survival game show, where a staggering prize of ₩1 billion (approximately US$1 million) awaits the sole survivor. The show is hosted by producer Jang Min-cheol](/person/park-hee-soon), who lays out the rules before launching the first challenge: a team raft competition. However, the excitement quickly turns to dread when, following a vote among the contestants, Choi Wook-hwan](/person/lee-chun-hee) is eliminated and mysteriously disappears, leaving only his belongings and passport behind.
The following day, the remaining contestants must locate six arrows that have been hidden throughout the forest. In a shocking twist during this challenge, they discover one of the arrows embedded in Choi Wook-hwan’s corpse, uncovering a dark secret: he was murdered by Jang Min-cheol after his elimination. As tensions rise, Lee Bo-young](/person/go-eun-ah) confronts Jang PD when she realizes that the game has escalated into a deadly killing spree, only to meet her own tragic end at his hands.
Desperate to escape from the clutches of this treacherous game, the contestants face an omnipresent threat as Jang PD monitors their every move through hidden surveillance cameras scattered throughout the area. Stranded in the harsh Australian desert, they are forced to participate in yet another challenge to reach an oasis. This desperate situation leads to additional fatalities, narrowing their numbers down to just five survivors.
As they fight for survival against the ruthless landscape and each other, one by one, contestants perish. Ha Seung-ho(/person/kim-hak-seon) meets his demise while traversing the desert, and Hong Soo-yeon](/person/yu-na-mi) is killed attempting to cross a river alone. The cameraman, Seo — who was under Jang PD's orders to document everything — also makes a fateful decision to confront Jang PD, ultimately resulting in his own death. In a heartbreaking betrayal, Kim Ji-eun](/person/jung-yu-mi), who had formed a bond with Park Cheol-hee](/person/lee-min-ki), finds herself murdered by him as he seeks to secure the prize money for himself. Ultimately, only Jo Yu-jin](/person/shin-min-a) emerges as the final survivor, returning to South Korea with the haunting memories of her ordeal.
Once the footage of these harrowing events is uncovered online, Jo Yu-jin is taken to a hospital and questioned by the authorities. As the broadcast ceased following the intense altercation between Han Gi-tae](/person/park-hae-il) and Park Cheol-hee, investigators depend heavily on Jo's recounting of the last events. According to her account, Jang PD forced the final two survivors, Jo and Han, into a nerve-wracking game of Russian roulette. Han, in a desperate act, tries to shoot Jang PD after pulling the trigger multiple times without result, but the gun fails to discharge, allowing Jang PD to shoot him instead. In retaliation, Jo uses the same weapon to shoot at Jang PD, causing him to fall from a cliff. Though injured, she manages to escape, carrying Han with her, only for him to succumb to his injuries before being rescued by the Australian police.
Despite her assertion that she acted out of self-defense, a doctor suggests that Jo should recover at home. On her way back, she receives a startling call from a phone hidden within a medicine bag, revealing that Jang PD is alive. He chillingly informs her that the gun used in the final game was unloaded, and he had orchestrated his own death as part of a much larger plan that included the ₩1 billion prize. He then provides Jo with the whereabouts of the money.
Returning to her former workplace at a convenience store, Jo uncovers the cash, but the memories flood back — memories of a tragic incident that spurred Jang PD's actions. Two years prior, his wife was brutally attacked and killed outside the very building, with eight witnesses, including the contestants, standing by without intervening. Among them, Han Gi-tae recorded the act instead of providing aid, while the others turned a blind eye to her cries for help. After exacting vengeance upon his wife's murderer, Jang PD sought retribution against those who had failed to help, by crafting this twisted survival game, forcing the spectators to endure the same terror his wife experienced.
Upon grasping the full scope of Jang PD's motivations, Jo questions him from the rooftop about whether his thirst for revenge has been quenched. In a mournful act, Jang PD commits suicide, jumping to his death as Jo leaves the scene, clutching the hard-earned prize money, a bittersweet reminder of the chaos that unfolded.