In the outskirts of a seaside town, a woman with a loaded gun is approached by a young man who expresses his surprise that she’s alive. Nine months earlier, she wakes up next to her husband, Jeff, to the sounds of their toddler, Abbie, crying. At breakfast, her son, Jake, puts on his school uniform while she argues with her husband. Abbie deliberately drops an egg on the floor and the parents resist laughing. Suddenly, while cleaning up, the mother gets angry and her toddler swipes her arm with a fork. The woman throws a chair at her furious husband and Jake bites his father. The woman stabbed her husband in the stomach with a carving knife. He knocks her out in return and when she comes to she is on the floor, facing her dead daughter. 

She finds her husband lying in a pool of blood but alive. He tells her that he killed both of their children and thought he’d killed her, too. However, Jake is not dead and rises from the floor to be with his mother. He tells his mother that he wanted to hurt her. Outside, people lay injured and dead on the street. The TV station is static and someone on the radio is sobbing. Her husband dies and the woman knows that she has to get her and Jake out of the house and they walk to Marcus and Angela’s house. At the house, they find Angela and her child dead and Marcus comes out of the front door holding a pistol. Marcus hands the woman his gun and says that if the moment of rage happens again she should shoot him. Together, they bury his wife and child. 

Marcus takes the pistol from her and puts it in the garden where his dead family lies. The next day, she and Jake leave the house and meet up with strangers and go to the council offices to find smoke coming from the building. They walk instead to a nearby church where a woman says that there must be a reason why they survived while others didn’t. Another person says that all the survivors are murderers, which causes a fight to break out. Two days later on BBC, a government spokesman tells listeners that on August 3rd at 8:14 a.m. everyone in the world experienced uncontrollable rage. He says that the government is trying to reform but they aren't sure if it will happen again. 

Twenty-two days after the first episode, the mother shoots Jake and he dies. After that, she is on her own, sleeping in abandoned homes and supermarkets. She drinks herself unconscious and evades lines of fire and other assassination attempts. One morning, she wakes up after drinking to find herself dressed in men’s pajamas in the company of an elderly man named Tim who has hooked her up to a saline drip. He tells her he found her in an unconscious state and took her in. When she tries to leave, he tells her he’s been tracking the episodes and predicts the next one likely won’t happen for another few days. The episodes always happen between 7 and 9 a.m. usually around every 21 days. 

Tim and her live together and during danger periods they lock themselves away from one another. Tim, who was previously an environmental activist, theorizes that the outbursts are a result of the Earth putting itself in balance. Tim asks her to have a baby with him and during a safe period she kills him. 

Two months later, she encounters the young boy and he reminds her of Jake. The boy tells her he thinks it’s aliens that are causing these outbursts. She tells him that’s a crazy idea. When he starts to creep her out, she grabs her gun but he beats her to it and tells her he was crazy even before the raging started.