An old man in a wheelchair listens to radio news announcements of a heat wave across Germany. A young nurse arrives at his house to find the door is unlocked, and the man is missing. As she tries looking for him he appears and kills her. Text appears telling the viewer that a long time ago, old people were thought to have an avenging spirit in some of them, which would take full control of the weakest members and drive them into a seemingly blind rage against the world. We meet main character Ella as she drives along with her two children Laura, and Noah on their way to the marriage ceremony of Ella's sister Sanna. Ella had divorced her husband Lucas resulting in an argument with her father, Aike. Lucas is now involved with a woman named Kim having stayed in the countryside. Sanna informs Ella and the kids that Aike has been put up at the local retirement house since she left. Ella decides to go there and bring their father back for the night's celebrations, and they take Noah along. The retirement home appears derelict and less than hygienic; various residents sit around desolately. They meet Lucas' new partner, Kim, who works there. As Ella tells Aike that they are here to take him home for the wedding, young Noah sees one of the other residents, an old man, staring at them. That evening, the same man rallies all the other old people to kill the orderlies in the retirement home before they leave en masse, heading into the night. After the wedding, Kim and Lucas spot an old man from the retirement home out in an open field, as well as a number of cars stopped on the road with dead people inside. Lucas drives his car back to the country house, where attacks had already begun. Many guests are killed including the newlywed couple. The noise of the attacks wake Ella up, who is unaware of the full breadth of the situation. Ella finds Sanna and her husband dead, and she herself has to jump out of the window to escape a horde of old people. She realizes she can't find Noah or Aike, so her, Lucas, and Kim all search for the pair. Eventually he is found in the attic, and tells everyone his grandfather had told him to hide there before joining the horde himself. The old people harm and kill everyone who has somehow broken families or expressed their doubts about love, further playing into the idea that it's all a result of a curse. Kim intentionally puts Laura into harms way as a result of her insecurity over Lucas' love for her vs his kids, and while Laura is able to survive, Kim also manages to push Ella out of the house and lock the door behind her. The old people attack Ella, as her children and Lucas try frantically to save her, which leads to Kim sacrificing herself, either out of guilt, despair, or love for Lucas. Thanks to her distraction, Ella is able to get away, and back inside the house. To escape from the old people attempting to break into the house, they use an old tunnel that leads to a nearby cabin. During the escape attempt, both Ella and Lucas are killed, managing to protect their children as they do so. On the other side of the tunnel, Laura and Noah discover it is now daylight, and their phones work again. Laura calls Alex, a boy she was shown to be romantic with, and instructs him to meet them at the beach with his boat. Before they can escape, they encounter their grandfather Aike. She points a gun at him but before she can do anything the leader of the old people tries to kill her. Facing death, she tries to sing their family song, and Noah joins her. The curse is weakened by this display of love, and Aike manages to get the gun and shoot the leader. This is what happens here, and ultimately, Aike takes up the gun and kills the leader. The kids and Aike all go to the beach together where Alex is waiting on a boat.