We can pick away at the merits of last year’s thriller “The Purge” (my big problem was that the characters had to do stupid things to keep the plot moving), but the movie definitely had a wild idea. For one night every year, the U.S. government sanctions lawlessness, allowing citizens to purge their baser instincts and thereby creating peace the remaining 364 days of the calendar.

That film was set mostly inside a single well-barricaded home. The sequel, “The Purge: Anarchy,” lets the concept out in the streets and goes crazy with it.

It’s a big improvement on the original. The same writer-director, James DeMonaco, is at the helm, but it’s as though the looser format allowed for more inventiveness.

Five people find themselves outside on the night of the Purge. Single mom Eva (Carmen Ejogo) and her teen daughter Cali (Zoe Soul) are rousted out of their apartment by mysterious uniformed troops.

A young couple (Zach Gilford, Kiele Sanchez) get stuck outside when their car is sabotaged. And a lone warrior without a name (Frank Grillo, from “The Grey”) is actually out on the streets by choice.

He’s decided to use the Purge to take revenge against one person. But first he gets saddled with these four helpless innocents, even though he ought to just ignore them and go about his bloody business; but there wouldn’t be much of a movie if he did that.

The film has a bargain-basement feel that’s somehow appropriate for the genre. Its terse antihero is the same guy you’ve seen countless times in movies like this, but that’s part of the appeal; who needs deep characterization when the point is simply to endure the night with the most likely guy to survive?

Grillo mostly nails the role, and Carmen Ejogo (great in “Sparkle” a couple of years ago) provides unexpected gravity. I will admit there are a few examples of characters doing stupid things, but the threats are so constant you have to begrudge a few whoppers.

In its final reels, “Anarchy” goes fairly berserk-o, and in its own pulpy way it takes up the cause of the 99 percenters. Let’s just say that society’s elite come across about as well as they do in “The Hunger Games,” but without the reassuring sheen of a big Hollywood production.

No, “The Purge: Anarchy” is down and dirty, and made out of spare parts. But when those parts are working in tandem, it gets a pretty good racket going.

“The Purge: Anarchy” (three stars)

The government-sanctioned night of lawlessness catches five people on the downtown streets; a terse lone warrior (Frank Grillo) is their best hope for survival. A big improvement on the 2013 “Purge,” this one’s a down-and-dirty suspense movie with a pulpy political thrust.

Rating: R, for violence, language

Opening: Friday at Alderwood, Cinebarre Mountlake Terrace, Everett Stadium, Galaxy Monroe, Marysville, Oak Tree, Pacific Place, Varsity, Woodinville, Cascade Mall.