If you’re a first-time visitor to the twisted America in James DeMonaco’s “Purge” franchise, here’s what you need to know: For one night each year, all crime, including murder, is legal. It’s a national release valve that reduces the overall crime rate. More important, it culls poor minorities while ensuring the safety of wealthy, well-protected whites.

Critics have largely dismissed the “Purge” movies as pandering action-horror fare (which they are) full of bargain-basement social allegory (which is true). Nevertheless, DeMonaco deserves credit for tackling issues of race, income inequality and government complicity with admirable bluntness. There are no nuanced metaphors in a “Purge” movie.

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Number three in the series, “The Purge: Election Year,” benefits from shrewd timing. Although there’s no orange-haired authoritarian running for president here, there is a woman, Sen. Charlie Roan (Elizabeth Mitchell). Roan looks a little like Sarah Palin and is campaigning as a Washington outsider. Her promise to end the Purge has her surging in the polls, but first she must survive the night. Her security chief is Leo Barnes (Frank Grillo, returning from 2014’s “The Purge: Anarchy”).

As in the previous films, the pre-Purge lockdown scenes effectively build tension. A black deli owner, Joe (Mykelti Williamson), hunkers down with his Mexican-American employee, Marcos (Joseph Julian Soria). Laney Rucker (Betty Gabriel) hops into her makeshift ambulance to help still-breathing victims. Dante Bishop (Edwin Hodge, now on his third “Purge”) runs an underground triage center. They’ll all come together to help Roan and Barnes, who have been betrayed, ambushed and forced onto some very mean streets.

“Election Year” doesn’t have the wild imagination of its predecessors, although Brittany Mirabile is memorable as Kimmy, a blood-soaked schoolgirl with a Minnie Mouse hairdo and a machine gun. DeMonaco’s directing still feels stagy; this “Purge” is the choppiest and least artful yet. Still, it works as quick and dirty entertainment, and it’s not mindless. That’s more than you can say for just about anything else in theaters right now.