Welcome to America where one night a year all crime is legal

The Purge is a night where all crime is legal and all hospitals, fire stations and police stations are closed down for 12 hours. A couple are driving home to their kids when their car runs out of gas just as the Purge commences, and they flee from masked attackers on motorcycles and minibikes. Meanwhile, a man goes out into the streets to get revenge on the man who slaughtered his son. Also, a mother and daughter run from their home after assailants destroy it. The five people meet up with each other, as they run through Los Angeles to survive the deadly night.