In 2014, a totalitarian political party called the "New Founding Fathers of America" are voted into office following an economic collapse, and pass a law sanctioning the "Purge", an annual event wherein all crime is legal and emergency services are temporarily suspended. By 2022, the United States is said to have become virtually crime-free, with legal unemployment rates having dropped to 1%. James Sandin returns to his home in an affluent Los Angeles gated community to wait out the Purge with his wife Mary and their children, Zoey and Charlie. The family is assured the security system manufactured by James' company will keep them safe, while Zoey meets her boyfriend Henry. As the year's Purge begins, James enables the security system and the family disperses to go about their normal routines. Zoey returns to her room and finds Henry, who had snuck in before the security system was engaged, planning on confronting her father about their relationship. Meanwhile, Charlie watches the security monitors and sees a wounded man calling for help. He temporarily disables the system to allow the man inside, but James races to re-engage the system and holds the man at gunpoint. Henry comes downstairs and points a pistol at James and opens fire, but then James returns fire and mortally wounds Henry. During the chaos, the stranger disappears. Through the surveillance cameras, the family sees a gang of masked, heavily armed people arriving at the front lawn. The leader demands the homeless man, warning that failure to comply will result in an invasion. When Mary asks about the security system, James admits it is incapable of withstanding a determined assault. The family find and capture the stranger to give him to the gang, only to realize that they would not be any better if they did and choose to defend him and themselves. After the deadline passes, the gang breaks into the house. James fights back and kills several of them before the leader stabs him. Charlie notices the nei