That's the logic-defying premise of "The Purge," in which crime is at an all-time low in the United States thanks to this 12-hour holiday for crooks and criminals. As Ethan Hawke explains to his son in a new trailer, "Tonight allows people a release from all the hatred and violence that builds up inside them."
Hawke's father character, James, has created a "Panic Room"-type barrier for his entire house to keep his wife (Lena Headey) and kids safe. "Everything is going to be OK," he assures them -- which, of course, means it's not.
When his son (Max Burkholder of "Parenthood") lets in a beaten-up stranger, the situation quickly turns dangerous when a bloodthirsty gang demands his release so they can exact their "purge" on him.
Guess Hawke really likes the "a few good guys defending their turf from a bunch of bad guys" genre, since he's teaming up again with his "Assault on Precinct 13" director James DeMonaco. Out on May 31, "The Purge" will be a huge pendulum swing from Hawke's other summer movie, "Before Midnight," which hits theaters the week before.