Nursery teacher Jenny (Reilly) and her boyfriend Steve (Fassbender) go on a camping holiday to the idyllic Eden Lake, soon due to be overtaken by a gated community, where Steve plans on proposing to Jenny.
After they arrive and attempt to relax, a local gang of chavs (lower-class British youths), led by a particularly unhinged boy named Brett, begin to infringe upon their time together and continuously ignore Steve's requests for peace.
After one chance encounter, the gang's mischievous rowdiness turns to horrific rage, unleashing a whole new side of their danger that throws the couple's vacation into an immediate downward spiral.
What was once the setting for a beautiful getaway turns into the grounds of a fight for survival as the couple are dragged into an increasingly brutal cat-and-mouse game, and must do whatever it takes to get out of the woods.
This film provides examples of:
- Abusive Parents: They're seen on three occasions: first, Jenny and Steve witness a mother slap her child very strongly for running within the pagoda of the restaurant; later, Steve witnesses Brett's father call his son maliciously and threateningly while he's within his house; thirdly, Jenny witnesses Brett's father smack Brett across the face after the latter refuses to obey him.
- Agony of the Feet: While running, Jenny impales her left foot on a metal spike sitting upright on the ground. With the spike protruding through the top of it, she removes it from her foot by pushing it all the way through.
- The Bad Guy Wins: Implied: with Jenny soon to be dead and his father having promised to ensure the town tells the police false information, Brett deletes the videos of the crimes of his gang.
- Bad People Abuse Animals: Brett and his gang are showing abusing a rabbit and a fox.
- Camera Fiend: Brett uses Paige to film the gang's acts of torture and murder.
- Car Fu: After stealing Steve and Jenny's car, Brett attempts to run them down with it. Later, Jenny steals Reece's van and drives off. On the way out of the forest, she sees Paige on the road and runs her down. The fact she accelerated on seeing her shows it was not an accident.
- Cavalry Betrayal: While trying to escape the forest, the injured Jenny meets Adam: the young boy she had encountered the day before. He agrees to show her the way back to town, but instead delivers back into the clutches of the gang.
- Cruel and Unusual Death:
- Steve. He's tied up with barbed wire and then stabbed in his arms, stomach, and mouth before being left to bleed to death. As if that wasn't enough, his corpse is set on fire right in front of his own fiancee.
- Adam, the youngest character in the movie, has a small tire forced upon his head by Brett before being doused in gasoline and set on fire, which doesn't even kill him instantly.
- Cruel Twist Ending: An oncoming vehicle hits Jenny's stolen van on the side as she drives it to escape Eden Lake, and she crashes into the yard of a house during a party. The party members assist her within the house and reassure her. Then, as they learn via phone call of the children Jenny killed, Jenny learns that the owners of the house are Brett's parents and that Paige and Cooper's parents are among the guests. Brett's father takes her into his shower with two other men, all but confirming her death.
- Don't Go in the Woods: Played straight and lampshaded. While driving with Jenny through the woods to Eden Lake, the GPS vocally advises Steve that he's going the wrong way and ought to turn around. It's never explained why.
- Downer Ending: Neither Jenny nor Steve make it out of their horrific ordeal alive, and not an ounce of justice is brought at the end of the day, with every chip seemingly falling into place such that their perpetrators get away scot-free. Steve dies in Eden Lake from his wounds inflicted by the gang, and although Jenny manages to escape the woods, she falls into the hands of the gang's parents. Brett's father promises to silence the town when the police arrive and murders Jenny in the shower, while Brett deletes the mobile phone videos containing footage of the gang torturing and murdering.
- Evil Laugh: As Steve's corpse burns, Brett jumps up and down, laughing.
- Extremely Short Timespan: The events of the film unfold over a single weekend.
- Final Girl: It's Jenny against Brett and his gang, but she loses to his father.
- Garbage Hideout: Jenny hides from Brett and Cooper in a dumpster half full of rotting and garbage and stagnant water, and submerges herself below the surface when Brett opens the lid. The stench is so bad it makes Brett gag and he fails to notice her.
- Giving Them the Strip: Jenny's sleeve gets snagged on the inside of the door when she is reaching into the hut in an attempt to grab the radio on the desk. As she is struggling to free herself, she sees the gang approaching. Unable to free the sleeve, she winds up pulling off her hoodie and leaving it in the doorway as she escapes.
- Hillbilly Horrors: Takes place in a British countryside town inhabited by murderous chavs.
- Hope Spot:
- Leaving a mortally wounded Steve in hiding, Jenny searches for power lines of which Steve reminded her and by which she believes she can find her way into town. She finds them and follows them until she impales her foot on an upturned spike, which wounds her and immobilizes her long enough for one of the town teens to find her.
- Zig-zagged in the final segment. After stealing a van, Jenny drives to leave Eden Lake until the car's struck on the side by an oncoming vehicle, and she crashes into the yard of a house, with locals having a party. They assist her after she asks and agree to help her before she realizes that the home is owned by Brett's parents and that several of the others' parents, including Cooper's, are in attendance. Upon realizing that she murdered two teens, their opinion on her takes a 180, and Brett's father kills her in the shower.
- It's Personal: Things go downhill real quick for Steve and Jenny after Steve kills Brett's dog.
- Jerk with a Heart of Gold: Steve, who is a bit too aggressive with the gang.
- Karma Houdini: The entire gang except Paige, Harry, and Cooper.
- Lower-Class Lout: The Movie. The kids are all portrayed as working-class at best with stereotypical hallmarks.
- Man on Fire: Brett and his gang tie Jenny and attempt to incinerate her. After she escapes, the put a tyre around Adam's neck and threaten to set fire to him if she doesn't return. She doesn't and they do.
- My God, What Have I Done?: Heartbreakingly, Jenny after accidentally killing Cooper, one of the more reluctant members of Brett's gang.
- Nothing Is Scarier: We don't see what happens to Jenny. We only hear the screaming...
- Papa Wolf: Brett's father, who murders Jenny once he learns she murdered two members of Brett's gang.
- Peer Pressure Makes You Evil: If not for Brett, the gang wouldn't have gone to such horrifying extremes.
- Perilous Marriage Proposal: From beginning to end. Steve and Jenny are only in the country and down at the reservoir so Steve can propose to Jenny, which is how they cross paths with the chavs. Jenny then finds the ring and Steve gives her an Anguished Declaration of Love as he's bleeding from being brutally tortured. He's cut off by being set on fire and murdered, and Jenny is dead before the weekend is out.
- Pet the Dog: Literally, with Brett's affection for his dog. It's after Steve kills her that Brett's intent turns murderous.
- Ring of Fire: Downplayed: after Jenny breaks free of her binding to the burning stake, she grabs a container of petrol, pours some between her and the gang, and lights it, making a chase difficult.
- Screw This, I'm Outta Here: Shortly after finding Cooper's body and witnessing Brett beat Harry to a dead pulp, Paige decides she's had enough and flees. Unfortunately, she runs into the path of the van Jenny's driving, and Jenny's feeling self-righteous.
- Slobs Versus Snobs: Steve and Jenny are both middle-class (Jenny is a teacher, Steve is an office worker), and are both the heroes (though Steve has some jerkish qualities), while they're set upon and brutally tortured by lower-class teenagers and their parents.
- The Sociopath: Brett.
- Teens Are Monsters: Dear God, yes. The chavs execute malicious, escalating torture and murder on Steve and Jenny, and, in the moral and emotional turmoil that they create, Brett kills Adam and Harry.
- Tongue Trauma: After capturing Steve, Brett orders Cooper to cut his tongue. Cooper doesn't quite manage it, but does severely mangle his tongue.
- Vomit Indiscretion Shot: Harry throws after Brett forces him to cut Steve, and all of the gory detail is captured on camera.
- Water Wake-up: Jenny is captured by the gang and knocked out. She wakes up as petrol is splashed in her face, and discovers she is tied to a pyre and the gang is preparing to burn her and Steve's corpse.
- Would Hurt a Child:
- Brutally Deconstructed with Jenny. As a schoolteacher, she'd normally never lay a finger on any child, but as a result of the situation she's found herself in, and specifically after being betrayed by Adam to the gang, she's forced to take them on for self-defense. And doing so has negative effects each and every time. She ends up killing two gang members by the end of the movie, both of which were the only ones to actually realize the harm they were causing. But the worst part is when the parents of those kids find out what she's done to them...
- Played straight with Brett, who kills both Adam and Harry.