You're Next (2011)

A couple, Talia and Erik Harson, have sex. After a shower, Erik finds the message "you're next" written on the window in Talia's blood, and her body lying dead on the ground. An intruder wearing a lamb mask kills Erik with a machete.

Erin accompanies her boyfriend, Crispian Davison, to a family dinner at their vacation home in rural Missouri. Present are Crispian's parents Aubrey and Paul, Crispian's older brother Drake and his wife Kelly, Crispian's younger brother Felix and his girlfriend Zee, and Crispian's younger sister Aimee and her boyfriend Tariq.

During dinner, an assailant in a tiger mask shoots crossbow bolts through the window, one of which hits and kills Tariq. The others try to contact the police, but discover that their cell phone reception has been jammed. Aimee runs outside to get help, but runs into a garrote wire, fatally slashing her throat. A distraught Aubrey retreats to her bedroom, but another intruder in a fox mask kills her with a machete before writing "you're next" in blood on the wall.

Kelly flees the house and goes to Erik's house nearby, where she finds his corpse. Lamb kills her by ramming an axe into the side of her head. Crispian leaves the house to look for help. Tiger attacks Erin but she stabs his arm, then smashes his kneecap and bludgeons him to death with a meat tenderizer.

Paul finds sleeping bags, food wrappers, and bottles of urine in the closet, indicating that the perpetrators have been hiding out in the house for some time. He presents this evidence to Felix and Zee, proclaiming that this was a targeted attack and not a random act of violence. Fox then approaches from behind and slits his throat. Felix and Zee emotionlessly watch him die, before Felix admonishes Fox for having killed his father right in front of him; the murderers are revealed as assassins hired by Felix and Zee to murder the family so the two could collect their inheritance. Meanwhile, Lamb finds Tiger's corpse and becomes enraged. He discovers a wounded Drake, but retreats after Erin stabs him in the back with a screwdriver. While setting up nail traps, Erin explains to Zee that she grew up in a survivalist compound, where she learned combat and survival skills, unaware Zee was one of the people responsible behind the event. While they are looking for tools to use as weapons, Felix reveals to Drake that Kelly has been killed. He then stabs Drake to death with several screwdrivers.

Erin is attacked by Fox and jumps through a window to escape, injuring her leg. She hides in the woods, but is chased back to the house by Lamb. She sneaks into the house and hides behind a curtain. Lamb, climbing through the window, is injured by one of the nail traps. Erin overhears an argument between Felix, Zee, Fox, and Lamb where Felix learns Lamb and Tiger were brothers, and revealing to Erin that Felix and Zee are behind the events. Her phone receives an alert stating that one of the emergency texts she was attempting to send to 911 has gone through. She ambushes Lamb before fatally stabbing him.

Realizing she cannot outrun Fox with a wounded leg, she sets a trap at the front door with Lamb’s axe, positioning it above the door to fall and kill anyone who opens it. Fox re-enters the house through the window, but is lured into the basement and killed with a log. Zee and Felix attempt to kill Erin themselves, but she kills Felix by pulverizing his head with a blender before impaling Zee in the top of the head with a knife. When Felix's cell phone rings, Erin answers the call without speaking. Believing he is speaking to Felix, Crispian reveals his involvement in the scheme. Erin confronts him when he returns. Crispian tells her that she was never meant to be targeted and attempts to bribe her into staying quiet. Disgusted that he would sacrifice his family for money, she kills him by stabbing him in the side of the neck and eye.

A police officer arrives and shoots Erin in the shoulder, having seen her kill Crispian. He enters the house, despite Erin's attempts to dissuade him and falls victim to the axe trap.