Ian Smith and Samantha "Sam" Shaw are a couple taking a romantic trip for New Year's Eve in the outback. They head to a remote beach for a weekend getaway from the pressures of city life. On the way, they meet German, a man who advises them to set up camp at a beach near a waterfall. When they arrive, they set up camp next to an abandoned campsite with no trace of its occupants. Sam suggests to Ian that they should get married and Ian happily agrees.After a few nights, they become concerned when they discover a traumatized baby on his own. Elsewhere, German tells his associate, Chook, about Ian and Sam, and the two begin to make plans. Chook is so excited to "go hunting" that he leaves early that morning without German. Chook finds Ian and Sam with the baby, Ollie, stuck at the campsite with a flat tire.Three days earlier, the Baker family - Robert, Margaret, their 16-year-old daughter Emily and their infant son, Ollie - had been camping at the same place. German and Chook showed up at the campsite and kidnapped Robert, Margaret, and Emily, unaware of Ollie's presence. German and Chook raped Margaret and Emily, and torture the family before murdering them all. After spotting Ollie in a photo on Emily's cell phone, they returned to search for him, but he had wandered off.Back to the present, Chook persuades Ian to go and search for the missing family. However, he intends to take Ian up to the killing ground to taunt him with the corpses as part of his sick game. When they arrive, the pair discovers that Margaret didn't die from her injuries and crawled off to the creek. Ian tries to save her, but Chook shoots and kills her on the spot. As Chook explains his intent to rape Sam and kill him, Ian charges forward and knocks him down. But rather than fighting Chook, Ian runs off in a panic as Chook chases him.Meanwhile, German arrives at the campsite to find Sam alone with Ollie. German tries to abduct Sam from the car, but she slashes his wrist and escapes with Ollie into the woods. German releases his dog, Banjo, to attack them. However, Banjo gets distracted by a wild boar and leaves German to chase after them instead.Chook mistakenly shoots German, thinking he is Ian. Chook apologizes to German as Ian watches from a hiding spot. Nearby, Ollie begins to cry, giving away Sam and Ollie's location. Ian attempts to retrieve German's sniper rifle, but he is too afraid and returns to his hiding spot. Chook kills German, who begs him to end his suffering. Chook snatches Ollie from Sam before slamming him to the ground. Chook then takes Sam hostage and tells Ian he will be waiting at the killing ground.After Chook leaves with Sam, Ian stops hiding and notices German's car keys protruding from his pocket. Meanwhile, Chook grows impatient that Ian hasn't come to save Sam, so he threatens to rape her. Right then, he hears Ian escaping in German's truck. Chook angrily drags Sam off with him as they attempt to intercept Ian. When they pass German's corpse, Sam notices that Ollie is missing. Once inside Chook's car, he insults Ian for abandoning Sam, but Sam believes that Ian took Ollie with him. Sam tries to fight Chook, leading to him crashing into a tree, knocking them both unconscious.As night falls, Ian arrives at the police station and asks for help. He accompanies two officers to the campsite. Sam awakens in the wreck of the car with her hands tied to the steering wheel and Chook absent. The officers spot the wreckage when Sam flashes the head beams on the car, but Chook kills them as they exit their police car. Chook shoots Ian in the arm and holds him hostage. He demands that Sam drive him to a safe location. Sam complies and runs up to save Ian from bleeding to death.Sam asks Ian if Ollie survived, but Ian tells her that Ollie was never with him and he ran off to the police as he didn't know what to do. Ollie is shown to have crawled away from German's corpse as Banjo sits silently guarding him. His final fate remains unknown.While driving out of the campsite, Sam resolves to stop Chook and violently crashes the vehicle. Ian falls unconscious, and Chook - badly injured - manages to get away from the wreckage. Sam scuffles with Chook for his handgun before she smashes his head with a large rock, finally killing him.In the end, Sam wakes up in a hospital and leaves her room to find Ian, recovering from his broken arm in another room. Sam stands silently beside his bed, with a look of sorrow and disappointment.