On the night of February 11, 2005, Helen and Joe Hackett return to a remote summer vacation home owned by Joe's parents after attending a friend's wedding reception. Shortly after arriving in the middle of the night, a young blonde woman, whose face is obscured by low lighting, knocks on the front door asking for a Tamara, but leaves after Joe and Helen tell her she is at the wrong house.
A short while later, Joe leaves to buy Helen a pack of cigarettes, when the woman returns and begins to pound harshly on the front door. Helen refuses to open up, locks all the doors, and tries to call Joe on her cell phone, which she discovers to be dead. She plugs it into the wall to charge near the fireplace and tries to call Joe on the house phone when the line goes dead. She returns to the fireplace to retrieve her cell phone, but it has disappeared. Helen then hears a noise coming from the back door. She grabs a large kitchen knife and opens the curtains, when sees a man wearing a sack mask over his head. Helen screams and trips over a record player, and it begins to skip repeatedly. The front door then opens slightly, and Helen peeks outside, only to see the blonde woman in a Dollface mask. She slams and locks the door before going to hide in the bedroom. After yelling "go away," the noises eventually stop, at which point she hears footsteps coming from the hallway, which turn out to be Joe's. As she explains what happened while he was gone, he tries to calm her down.
She frantically explains to Joe that she saw a man in a mask, and heard loud banging noises. Joe is not worried about the incidents, thinking that they were caused by some teenagers fooling around. He goes outside to his car, whose tires have been slashed and its windshield smashed in. As he searches the car, someone touches his back, but they run away before he is able to turn around and see them. Once he turns back to the car, he looks up and sees Dollface, and asks her to leave. After she runs off, Joe's sense of worry is heightened and he persuades Helen that they need to escape in their car.
As they are backing out of the driveway, a large truck pulls up behind them with its floodlights on, revealing another woman, this one wearing a Pin-up mask. After she smashes the truck into the couples' car, Joe and Helen run back into the house, where Joe finds a shotgun. As the couple approach the front door armed with the gun, the Man in the Mask begins breaking down the door with an axe. Terrified, the couple block the door with a piano, and Joe attempts to shoot him, but misses. The couple decide to hole up in a bedroom, facing the open doorway with the shotgun armed and ready. They hear footsteps in the house, and one of the intruders puts on a country record.
Joe's friend, Mike, who Joe contacted earlier, arrives at the house in his car. When he tries to call Joe's cell phone, it goes straight to voicemail. But while he is leaving a message, a rock crashes through his windshield, prompting him to jump out of the car. Baffled, he notices country music playing loudly from the house. He steps onto the porch and fails to notice Dollface hiding in the shadows there before entering the house. As Mike walks down the hallway, the Man in the Mask appears behind him, holding up the axe. When Mike steps in front of the closet, Joe fires the shotgun, thinking it is one of the masked killers, and kills Mike by shooting him in the face. After Joe and Helen realize they killed Mike, they decide to leave the house to get help.
Joe leaves the house first, promising Helen that he will return in a few minutes, but Helen decides not to wait for him to return, and leaves to go to a shed in the backyard. There, she finds a radio, which she uses to try and contact someone for help, but when she raises her voice, Pin-Up Girl hears her and smashes the radio. Helen finally realizes she was being watched the entire time she was outside and returns to the house to look for Joe. As she walks down the hall, she hears a few keys being played on the piano, followed by footsteps, and the lights suddenly shut off. The Man in the Mask enters the hallway, but does not notice Helen, as he is looking in the other direction. Helen hides in the kitchen pantry while the man searches the hallway. He sits down at the table a few feet away from the closet before leaving the room. Helen peers out of the closet, only to find the blonde masked woman staring back at her. The woman breaks the pantry door in, but suddenly stops. Helen exits the closet to find the woman waiting for her with a knife. Helen opens a kitchen drawer to arm herself as well when Joe is pushed into the house by the masked man, who now has the gun. When Joe tells Helen to run, she sprints for the front door, only to find Pin-Up girl blocking her way. She runs into a bedroom and slams the door before attempting to escape through the window, and suddenly the lights come back on and the door swings open. Helen walks back toward the hall to see who opened the door, when the Man in the Mask grabs her and throws her into the wall. She slowly loses consciousness as she is being dragged down the hallway.
Joe and Helen wake up the next day and find themselves tied to chairs in the living room while the three strangers stand over them. Before removing their masks, Pin-Up Girl walks into the kitchen and returns with a large knife. Each of the strangers then takes turns stabbing Joe and Helen seemingly to death. After they escape, Dollface shows feelings of guilt, and they stop the truck for her to ask two young Christian boys for a religious pamphlet, before continuing to drive away with Pin-Up Girl telling her that "It'll be easier next time." The two young Christian boys are then seen entering the house only to find Joe and Helen lying unmoving in the living room. One of the boys goes up to Helen, and as he is about to touch her, she grabs his arm and screams in terror.