2015 saw the rise of a radical new political party, the New Founding Fathers of America, to power in the face of economic collapse in the United States. In the years that followed, the NFAA institute a new national holiday known as "The Purge": every March 21, beginning at 7:00 PM, all crime in the nation, up to and including murder, become legal, and remains so until 7:00 AM the following morning, and emergency services like police, ambulances, and firefighters are shut down until the next morning. The only rules are that government officials with a clearance level of at least 10 are off-limits (their murder being punishable by public execution the following morning) and that explosive weapons were disallowed.
On this day in 2022, James Sandin, a salesman for an insurance company that specialized in covering damages incurred during the Purge, returned home to his wife, Mary, and his two children, Zoey and Charlie, to wait out the Purge, his affluent Los Angeles home being outfitted with security from James's work.
Once the Purge commences, James engages the security in his house, locking it down. Unbeknownst to the home's inhabitants, Henry, Zoey's boyfriend, had managed to sneak in before the home was locked down. He planned to confront Zoey's father, who didn't approve of the two being together.
Meanwhile, Charlie watches security camera feeds of the house. Through the cameras, he sees a wounded man begging for entrance into the safety of his home. Charlie disengages the security to let the man in. James, finding his security disabled, races to turn it back on and holds the intruder at gunpoint, just as Henry goes to confront James. James kills Henry in the ensuing gun fight while the intruder retreats into the house and hides.
As James admonishes Charlie for jeopardizing their lives, a gang of mask-wearing revelers comes up, their leader requesting James release the wounded man to them. Otherwise, they would "unleash the beast", breaking into the house and killing everyone inside. Sadly, James admits to Mary that their security system was meant only as a deterrent against intrusion: if someone wanted to break in, they could do so with relative ease.
The gang eventually use a truck to rip the metal plating from their front door, and gain entrance into James's home. Thankfully, the Sandins' neighbors, the Ferrins, come into their home and kill the gang members, with James tragically dying in the ensuing confrontation.
The Sandins' relief is short-lived, however, when Grace Ferrin reveals that she despises the Sandins, since they had made their wealth off of the sale of security systems to their neighbors. The Ferrins tie up the Sandins with the intent of killing them, but the wounded man that Charlie saved earlier comes to their rescue, killing one of the Ferrins and forcing the rest to free them. He asks is Mary wants to kill them in retaliation, but Mary opts to spare them instead.
Eventually morning comes, and at 7:00 AM on March 22, 2022, the annual Purge ends. The Ferrins return to their home as Mary thanks the wounded man for his aid.
The news report the following morning states that this year's Purge is the most successful to date.