In a dystopian near-future America, the government has sanctioned an annual 12-hour period known as "The Purge," during which all criminal activity, including violence and murder, is legal. The rationale behind this event is to allow citizens to release their aggression and ensure national peace the rest of the year. On the eve of this year's Purge, five individuals find themselves caught in the chaos of the city as the siren signals the start of lawlessness. Sergeant, a man seeking vengeance on the night of The Purge, prepares to venture out into the darkness with a specific mission in mind.

As the night unfolds, Sergeant encounters a struggling mother, Eva, and her daughter, Cali, who are dragged into the streets by a Purge mask-wearing force. Offering them protection, Sergeant's plans change, and they soon find themselves accompanied by a young couple, Shane and Liz, whose car breaks down just as the Purge commences. Together, this group of strangers must navigate a night filled with terror and violence, seeking safety. Trust is scarce and danger lurks at every turn, as they experience firsthand the horrors of a society unhinged by legal anarchy. Their journey through the city becomes an exploration of morality under the most extreme circumstances, as they struggle to survive until dawn.