A middle-class family, Amanda, Clay, and their teenage children, thirteen-year-old Rose and sixteen-year-old Archie, drive from their home in Brooklyn to a luxurious but remote Airbnb in Long Island for their summer vacation. They swim in the pool, stock up on groceries, and spend a day at the beach, but on the second night, their tranquility is disrupted by the arrival of an older Black couple who claim to own the house, G.H. and Ruth Washington. They also claim there’s been a blackout in New York City. Amanda is suspicious, in large part because Ruth and G. H. are Black, but she and Clay let the couple stay in the basement apartment. 

They awake to four news alerts on Amanda’s phone, the last one in gibberish. The TVs, Internet, and landline don’t work but they still have electricity. In the light of day, Amanda is less suspicious of the Washingtons and they begin to make small talk. It emerges that the Washingtons are wealthy and well-connected. As the adults talk, Rose sees dozens of deer in the woods behind the house, not realizing there are thousands of the animals gathering. Clay offers to drive to town to find out what is going on, but gets lost after stopping to smoke a cigarette. The others gather around the pool as if nothing has happened. The kids play with pool floats, Amanda and Ruth make sandwiches for lunch, and G. H. relaxes in the hot tub. 

Rose and Archie go exploring and find a shed. Archie scares Rose with a story of a sinister man who sleeps in the shed, then they wander into the woods. Meanwhile, Clay is still lost and begins to panic. He comes across a Spanish-speaking woman in evident distress on the road and drives away without helping her. Out in the quiet woods, the children spot another house but don’t approach it. Poolside, Amanda worries that Clay isn’t back. While she and G.H. are talking, an unidentifiable, ear-splitting noise terrifies them all. It is loud enough to make hairline fractures in the house’s plate glass doors. Amanda screams and runs to find her children, who are running home in fear. The noise terrifies Clay and makes him long for the safety of the house. Suddenly, he recognizes his surroundings and sets off for home. When the others ask where he has been, he lies because he is ashamed that he got lost. He doesn’t mention the woman on the roadside or his panic when he couldn’t find his way back to the house. Instead, he says he smoked a cigarette and came home when he heard the noise. 

Archie takes a shower and feels hot and sleepy afterward. It begins to rain, and Rose wishes their vacation could have lasted one more day. Ruth prepares to do laundry and considers asking Amanda to put hers in too, while Rose decides to bake a cake. Amanda asks Clay to fill the bathtubs as an emergency precaution after G. H. confirms that a power outage would mean they can’t get water. They discuss going home or to town but decide to wait. Amanda finds Archie asleep and feverish. He vomits and they decide to take him to their doctor in Brooklyn the next day. That night feels almost like a party, as the adults indulge in lots of food and alcohol. Ruth sees Amanda and Clay almost as friends now, herself as host. Amanda and Clay begin packing, then have sex to feel better. Amanda goes outside naked and G. H., in a swimsuit, joins her in the hot tub. Clay, also naked, brings drinks. A flock of flamingos lands in the yard and the pool, and everyone speculates about what their presence means. They go back inside and hear the terrible noise again. 

Amanda, Clay, and their children huddle in bed together. Amanda and Clay wake up feeling terrible and hungover. Amanda vomits a pinkish fluid and Clay has diarrhea. When Archie wakes up, five of his teeth fall out. Clay consults Ruth and G. H., who agree Archie needs to go to the hospital. Clay doesn’t know the way, so G. H. agrees to go with him even though Ruth wants G. H. to stay with her at the house. Then Amanda notices that Rose is gone. They search for her, but when Archie collapses and starts vomiting pinkish fluid, G. H., Clay, and Archie leave for the hospital. Ruth and Amanda argue as they search for Rose. Afterward, Amanda apologizes to Ruth and wants to hug her but doesn’t. 

Instead of going to the hospital, G. H. drives to the home of Danny, his contractor and supposed friend. Danny thinks a war has broken out and he offers them no help. His harsh demeanor makes it clear that he tolerated G. H. when he was making money from him, but he does not consider him a friend. In Danny’s mind, he dislikes G. H. for the same reasons he dislikes Barack Obama. To G. H.’s disappointment, Danny refuses to help or even to let them inside, but he warns them that the best thing to do is to stay home and wait. Instead of going to the hospital, they decide to return to the house. 

Unaware that people are looking for her, Rose is in the woods on a mission to do something helpful. Following the example set by the books and movies she loves, she believes they shouldn’t panic but prepare. She walks to the house she and Archie found in the woods. When nobody answers the door, she breaks in and explores the place, imagining her family could live there. She puts on a DVD to listen to as she takes stock of the food and other supplies. Then she heads back with a full bag of provisions and news of the vacant house.