"2 Guns" is a lighthearted action movie with a high body count, including a few dead chickens. The chicken scene comes about 10 minutes in, and it either depicts a scene of animal cruelty in a jolly way — or it’s an example of genuine animal cruelty on its own. Hard to say which.

The setup is that four or five chickens are buried in the ground up to their necks and some sadistic slobs are shooting at them. The bullets are missing them by inches, and they’re flinching, though with computer graphics these days, who knows what’s real and what’s not? Then Mark Wahlberg, who has been berating the other men for animal cruelty, demonstrates his skill with a gun by quickly blowing off the head of each chicken — and that last dead chicken? That looked real.

‘2 GUNS’ Rated: R Opens today

The interlude sets the tone for "2 Guns," in ways that director Baltasar Kormakur probably never quite realized. It establishes that the filmmakers think stuff is funny that isn’t, and it welcomes the audience to a brutal and stupid experience. But that’s not the worst. No, stupid brutality is simply this movie’s chronic illness — the fatal one is a story that seems made up on the spot and creates no reason to keep watching.

This is where having movie stars helps. See Denzel Washington doing his famous rolling walk down the street, and suddenly pleasant associations from other, better Denzel movies spring to mind. To a lesser but respectable extent, the same might be said for Wahlberg. The impulse is to care about these guys, and so "2 Guns" gets a whole lot of benefit as it creates a whole lot of doubt. Finally, after about an hour, every last ounce of audience good will evaporates, and the actors are left stumbling through the arid desert of the screenplay.

At its heart, there is a single almost-good idea: Washington and Wahlberg are a couple of shady characters, who team up for a major heist, each not knowing that the other isn’t really a crook. Bobby (Washington) is a DEA agent, and Stig (Wahlberg) works for Naval intelligence. They team up to rob a bank, because they want to put the squeeze on a big-time gangster who has $3 million on deposit there. In fact, they walk away with $47 million, a troubling sum of money.

A word about the gangster, who is played by Edward James Olmos. You know how they keep track of his comings and goings? They park outside his house and watch. That’s funny. When I was a kid I lived fairly near mob boss Paul Castellano, who had high fences and cameras and guards everywhere. Guys like that try not to make it easy for their enemies.

The heist brings about a whole set of complications, and it takes the rest of the movie to sort them out. The story has an improvisatory feeling, with one problem piled on another, which could have been all right, except that the screenwriters forgot the first rule of action movies: No matter how complex the story gets, the protagonists’ motives have to be simple and compelling.