Production companies Blinding Edge Pictures Blumhouse Productions
Produced by M. Night Shyamalan Jason Blum Marc Bienstock
Directed by M. Night Shyamalan
Written by M. Night Shyamalan
Starring Olivia DeJonge Ed Oxenbould Deanna Dunagan Peter McRobbie Kathryn Hahn
Cinematography Maryse Alberti
Edited by Luke Ciarrocchi
Synopsis Two siblings from Philadelphia, 15-year-old Becca and 13-year-old Tyler, prepare for a five-day visit with their grandparents while their divorced mother Loretta goes on a cruise with her boyfriend. Loretta reveals that she has not spoken to her parents in 15 years after marrying her high-school teacher, of whom her parents disapproved. Having never met their grandparents, the teens plan to record a documentary film about their visit using a camcorder. Becca and Tyler meet their grandparents, referred to as "Nana" and "Pop Pop," at a train station. When they arrive at their isolated farmhouse, Becca and Tyler are instructed to never go into the basement because it contains mold, and that bedtime is at 9:30 every evening, after which they should not leave their room. Although at first, the grandparents seem pleasant, their behavior gradually becomes peculiar. The first night, an hour past curfew, Becca ventures downstairs for something to eat and sees Nana projectile vomiting. During the day, Nana creepily chases the teens who are playing hide-and-seek. Later, Tyler finds a pile of soiled diapers in the shed. In town, Pop Pop attacks a man he thinks is following them. When challenged, both grandparents are dismissive of each other's behavior. As the erratic behavior intensifies, Becca and Tyler's documentary-style film evolves into one of mystery-solving and evidence collection. A woman Nana and Pop Pop helped in counseling brings a blueberry cobbler round to thank them, but following a confrontation, is not seen leaving. Concerned about her grandparents’ behavior, Becca checks the internet and concludes it is normal behavior for older people and a chat with Loretta reinforces this. Concerned about the events, Tyler decides to secretly film the living room during the night, but Nana discovers the camera and tries unsuccessfully to break into the children's locked bedroom with a knife. Upon watching the footage of Nana with the knife, Becca and Tyler video call Loretta and beg her to collect them. Upon showing Loretta her parents while they are outside, she unnervingly declares they are not her parents. Realizing they have been staying with strangers, the teenagers try to leave the house, and suddenly discover Nana and Pop Pop hanged the woman from a tree, and forcefully encourage them to play Yahtzee. Later, Becca sneaks into the basement and finds the decomposed corpses of their real grandparents, along with uniforms from the psychiatric hospital at which they worked, revealing the impostors as escaped patients. Pop Pop grabs Becca and imprisons her in his bedroom with Nana, who tries to attack her in a psychotic fit. He then tortures Tyler by smearing his face with his dirty diaper. Following a struggle, Becca fatally stabs Nana with a glass shard from a broken mirror, then runs to the kitchen and attacks Pop Pop. As Pop Pop gains the upper hand, Tyler knocks him to the floor and kills him by repeatedly bashing his head with the refrigerator door. The teens escape outside unharmed, where they are met by their mother and police officers. In the aftermath, Becca asks Loretta about what happened the day she left home 15 years ago. Loretta states that she had a major argument with her parents, during which she hit her mother and was then struck by her father. Loretta then left home and ignored their attempts to contact her. Loretta concludes that reconciliation was always possible had she wanted it. She then tells Becca not to hold on to anger over her father's abandonment, upon which she includes footage of him in the documentary after earlier saying she wouldn't do so.
