A once happy family struggles with bereavement when the father is hit by a car and killed. Unemployed and financially unable to support herself and her teenage son (Logan), the mom (Naomi) agrees to move into her sister's secluded mountain mansion until it sells.
On moving in, Naomi and Logan encounter their elderly neighbor, Martha, who behaves strangely, and Chris, a pleasant store clerk. Following an open house, a series of strange occurrences begin. Objects are moved, the phone rings but nobody speaks, the pilot to the hot water tank repeatedly gets shut off while Naomi is showering and there are numerous unexplained noises.
One night Logan wakes to a knock at the door and sees a car idling in the driveway. Upon going outside to investigate, Logan finds a disheveled and confused Martha who behaves abnormally and demands to know who he is before running off into the night. A few nights later, Martha arrives with banana bread and confesses that she came to the open house. She starts making comments about her husband that indicate that he is alive and Naomi questions her about this. Martha denies previously saying her husband died and leaves.
These events continue and eventually a repairman is called to inspect the faulty hot water tank. He seems familiar with the home and Martha. He reveals Martha has Alzheimer’s and that her husband did pass away. He finds Logan’s cell phone that went missing days prior and gives it to Naomi, leading her to believe that Logan had been messing with her by turning off the hot water pilot. She confronts Logan and they have a heated argument. That night Logan wakes to use the bathroom and it is revealed to the audience that there is someone else lurking in the home.
The occurrences gradually escalate. While out, Naomi receives a call from her sister, who tells her that a break-in was detected by the realtor hosting the open house. Naomi and Logan rush to the house to find music playing, a fire in the fireplace and a rotary phone on the dining table. The phone rings, but when answered, nobody speaks. The police are called and search the home, finding nothing further. Unable to afford a hotel, the mother and son are forced to remain in the home.
Logan contacts Chris, who agrees to stay the night on the couch after helping search the home. A loud thump wakes Logan in the middle of the night. He ventures outside to find Chris in the driver's seat with his throat slashed. An unidentified man abruptly grabs Logan and knocks him unconscious. The perpetrator douses Logan with a bucket of cold water, leaving him to the harsh winter elements while he goes after Naomi.
The man gets into bed with Naomi, who initially thinks that he is Logan. Naomi reaches for an envelope of photographs that she recently developed and is horrified to discover photos of her and Logan sleeping in their beds. At this time, the man sits up in the bed and she realizes it is an intruder. She is attacked and tied to a chair. The man brutally punches her when she attempts to scream and then breaks all her fingers. Knowing Naomi is unable to use her hands, the man taunts her by setting a knife nearby before leaving the room.
Logan wakes in the driveway, freezing and disoriented. He goes back inside the home and finds his mother, bound and bleeding. He takes the knife and stumbles through the house in search of a phone, violently shaking from the cold. He quickly finds the landline has been cut and that the SIM cards have been removed from both their cell phones.
Logan is startled by his mother screaming and rushes to help her. He follows her screams to the basement where he accidentally mistakes her for the killer and stabs her with the knife. Naomi tells him to run before collapsing. The killer gives chase, knocking Logan to the ground. The man easily overpowers Logan and holds him down while he removes the teen's contact lenses, leaving Logan unable to see clearly. Logan is able to break free and escape out the front door into the woods, albeit freezing and visually impaired. Logan hides by a fallen tree as footsteps approach. Unable to see clearly, he assumes that the footsteps belong to the killer but it turns out to be Martha wandering through the woods in the middle of the night. Martha leaves and we find that Logan has survived the freezing elements until morning.
Succumbing to hypothermia, Logan drags himself to a stream. He suddenly sees the killer’s black boots next to him. Weak and unable to flee, Logan screams as he is grabbed. The next scene shows Logan’s lifeless frozen body lying by the stream, apparently strangled or drowned.
The movie ends showing the unidentified man driving towards the next open house event.