While waiting outside a convenience store, teenager Logan Wallace witnesses his father Brian getting hit and killed by a speeding car.With Logan's mother Naomi struggling to make ends meet, Naomi's sister Allison offers for Naomi and Logan to stay in her vacant mountain house while it is on the market. The only condition is that Naomi and Logan must be elsewhere during open houses.On their drive up to the remote home, Naomi and Logan are frightened by the sudden appearance of a man in the road. While stopping for groceries, Naomi and Logan meet their odd new neighbor Martha, who mentions that her husband is also deceased.Upon getting settled in the house, Logan explores a long tunnel in the cellar. At night, a car in the driveway shines bright headlights and honks its horn before driving away. Logan goes outside and encounters Martha. Martha asks who Logan is and what he is doing on her property before wandering away confused.Naomi and Logan leave for the afternoon while Realtor Joannie McAllister and her associate Ed host an open house. Naomi and Logan discuss their family's debt problems over lunch. While shopping afterward, Naomi meets store clerk Chris. Logan takes a disliking to Chris when he seemingly flirts with Naomi.Naomi and Logan return home. Ed startles them as he rushes out the door. Logan mentions how odd open houses are because they allow strangers inside that no one monitors.Eerie occurrences begin plaguing Naomi and Logan. The phone rings, but no one speaks on the other end. Logan's cellphone goes missing. Naomi finds the hot water shut off during a shower. Someone slams the basement door on Naomi.Chris comes to the house claiming to be interested in purchasing the property. Naomi allows him to explore on his own.Martha briefly stops by. Martha mentions that Naomi should meet her husband. Naomi remembers Martha saying that her husband died. Logan later has another odd encounter with Martha.The hot water goes out again. A mysterious man is seen stalking around the house unnoticed.Naomi finds a crumpled family photo in the trash. A plumber who comes to inspect the water heater confirms that Martha's husband died, but adds that Martha suffers from Alzheimer's. The plumber also returns Logan's phone, which he found in the basement.Naomi confronts Logan with the cellphone and crumpled photo, accusing him of messing with her for revenge. Logan denies any involvement. The two of them have a blowout argument over Brian's death. Later that night, Logan has a nightmare involving his father.During the next open house, Logan goes for a run while Naomi goes into town. Naomi bumps into Chris. Chris gives Naomi his phone number and tells her to call if they ever need anything.Allison calls Naomi to warn that the Realtor reported a break-in. Naomi and Logan rush home. They find the dinner table set and Christmas music playing before receiving another silent phone call. Naomi calls the police, but officers find no one in the house.Logan decides to call Chris to spend the evening on the couch for peace of mind. Later that night, Logan goes outside to inspect a car in the driveway. He finds Chris dead in the front seat. An unseen man knocks Logan unconscious from behind.The man climbs into bed with Naomi. Naomi finds alarming photos taken by a stalker before the man violently attacks her.Naomi wakes restrained to a chair. The man tortures her. Naomi calls for Logan. Logan recovers and rescues his mother.Logan explores the house looking for a working phone or signs of the intruder. Startled while searching the basement tunnel, Logan accidentally stabs his mother. Naomi warns Logan to run before dying.The man chases Logan. The man manages to take out Logan's contact lenses, rendering him unable to identify his attacker. Logan flees outside and collapses. Martha briefly wanders by.Logan recovers in the morning. Logan runs to a nearby stream. The man catches up to Logan and murders him. The unidentified killer then drives off toward another open house.