Kristen McKay, portrayed by Liv Tyler, and James Hoyt, played by Scott Speedman, find themselves returning to a secluded summer home owned by James's parents late at night after attending a friend's wedding. The evening takes a dark turn when Kristen rejects James’s marriage proposal. A mysterious knock at the door introduces a young blonde woman who inquires, "Is Tamara home?" Upon being informed they have the wrong house, the woman walks away, but her presence lingers ominously.
While James steps out to buy cigarettes and clear his mind, Kristen is left alone. The blonde woman returns, but this time, Kristen refuses to open the door, insisting, "You already came by here." Tensions rise as the smoke alarm blares due to the fireplace being blocked, and while attempting to remedy the situation, Kristen becomes increasingly anxious. She locks all the doors and tries to contact James, but the phone line suddenly goes dead. As she seeks comfort in a glass of water, a masked figure appears behind her.
The chilling atmosphere escalates when strange occurrences unfold—items are inexplicably moved, and a series of knocks at the door send Kristen into a panic. She notices the smoke alarm suspiciously placed in the middle of a dining room chair and feels the creeping terror of being observed. Armed with a kitchen knife, she bravely ventures toward the sliding glass door, only to encounter the masked man who slams his hand onto the window, sending her into a scream of fright.
After a series of disturbing events, including James's return and his disbelief in Kristen’s anxiety, they catch a glimpse of the eerie blonde woman, now masked as Dollface, played by Gemma Ward, watching from the backyard. The situation spirals down when they discover their car vandalized, with James's cell phone missing, all while Dollface menaces them.
Attempts to leave the area prove futile as they face off against a series of terrifying figures: The Man in the Mask and another formidable foe in a Pin Up Girl mask. As they rummage through the house for help, they stumble upon a shotgun and realize they might need to defend themselves. Their situation worsens with the arrival of James's friend, Mike, who tragically meets his end due to a misfire from James, further compounding their terror as the assailants mockingly paint "KILLER" on the back door.
As darkness descends, the couple is left feeling hopeless. They encounter eerie moments where masked figures toy with them, heightening their emotional and psychological turmoil. Ultimately, their struggle for survival leads to a devastating encounter where Kristen, while tied up and dressed in her wedding gown, confronts her captors. When she asks, "Why are you doing this to us?", Dollface coldly responds, "Because you were home."
In the aftermath, dawn reveals a gruesome scene as Kristen and James are left in the grimmest of situations, their fates hanging by a thread, and the haunting realization lingers in the air that their nightmare was simply initiated by their being present. As the unthinkable happens, they become mere victims of a cruel fate, leaving the audience to grapple with the chilling implications of their harrowing ordeal.
