Ben Affleck apparently couldn't wait to star in his own Bat feature.

Or, to be more generous, he got so jealous of pal Matt Damon’s “Bourne” franchise he wanted an action saga to call his own.

Either way, “The Accountant” is one mixed-up movie.

The film begins with one of Affleck’s best performances. By the final reel, we’re watching a full-on action movie. You almost expect Damon to have a walk-on role. Or, at the very least, remind his old chum he left a pretty compelling story in the dust.

“The Accountant” casts Affleck as Christian Wolff, a math whiz on the Autism spectrum. That means he’s at ease with reams of numbers but struggles with social cues.

We learn through flashbacks how his parents dealt with the condition. It wasn’t easy. They feared he wouldn’t have a “normal” life, but they weren’t sure how to help. Some moments are played for laughs, but the film treats the subject with the proper understanding.

At first.

Turns out Christian will use his uncanny gifts for any ol’ client that comes his way. Drug cartels. Mob figures. If they can pay, he’ll cook their slimy books. That comes back to haunt him even though his unseen adviser steers him toward a more legitimate client.

FAST FACT: Every 11 minutes someone in the U.S. is diagnosed with Autism, according to the American Autism Association.

The government, in the form of a conflicted agent (Cynthia Addai-Robinson), is on Christian’s trail. So is a mysterious enforcer (the “Punisher” himself, Jon Bernthal).

Only this isn’t your garden variety accountant.

Christian has a particular set of skills. He’s as comfortable with a sniper’s rifle as with a fat stack of receipts. Seems Christian’s dad figured he might be bullied due to his Autism. Better teach him a little self defense, just in case.

By “little,” we mean he could go 12 rounds with Jason Bourne.

Along the way Christian awkwardly flirts with Anna Kendrick, cast as a fellow accountant who connects with his unvarnished soul.

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Affleck, heavy lidded and tonally flat, makes the most of Christian’s limitations. He’s endearing yet aloof. It’s easy to see how he forced his way into a world that doesn’t readily accept him.

The actor’s career flatlined a few years ago following a string of duds. He reinvented himself as a Oscar-nominated director. That allowed him to slip back in front of the camera without drawing snickers.

Consider Affleck 2.0 an improved model in every possible way.

What could he do with a movie boasting such a split personality? The film’s final reel discards Affleck’s fine-tuned performance in favor of generic action thrills. Suddenly, all that character development gets pushed aside for hand-to-hand combat and some serious gun fights.

Director Gavin O’Connor (“Warrior”) is better than this, frankly. And he clearly doesn’t have his heart in the bumpy transition.

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The third act crumbles with absurd exposition, delivered sans embarrassment by the great J.K. Simmons. And then the action takes over. O’Connor can’t connect the violence with what we’ve seen during the previous hour.

That, and a cutesy reveal we see coming miles away, shreds the story’s sense of proportion. You almost expect a title card saying, “Coming Soon: The Accountant 2: Audit or Die” right before the end credits.

By the time we “meet” the disembodied voice that counsels Christian’s career, we’re left to wonder if the film wasn’t mislabled out of the box.

Maybe Affleck signed on for a new, as yet-unknown superhero feature in between his Bat gigs.

HiT or Miss: A quiet, vulnerable Ben Affleck performance powers the first half of “The Accountant” before the film devolves into a frantic actin caper.

“DESIERTO”

Your ability to enjoy “Desierto” may depend on the color of your hat.

If it’s red and reads, “Make America Great Again,” you might have some real issues with the plot.

The movie revolves around a crude stereotype of those who want a secure U.S. border. Swallow that jagged ideological pill, and you have a thrill ride that leaves your whole body clenched in your seat.

The story’s political implications start, and mostly end, with the premise. The rest is pure adrenaline.

Gael Garcia Bernal plays a Mexican father sneaking into America across its porous southern border. He’s not alone.

He’s got his son’s Teddy Bear (awwww) for company along with a group of fellow Mexicans eager for that American dream.

The truck carrying them across the border breaks down, leaving them to finish their journey on foot. Turns out this part of the southern border features something far more intimidating than a wall.desierto-social

Jeffrey Dean Morgan stands between the immigrants and their new home. And he’s got a rifle he’s itching to fire.

“Welcome to the land of the free,” he grunts. Soon, the immigrants are running for their lives.

“Desierto” doesn’t depict the Mexicans as uniformly decent. The men shepherding the immigrants across the border are callous opportunists.

One is far too eager to engage in “locker room talk” and its logical conclusion. Still, writer/director Jonas Cuaron is unwilling to give Morgan’s character a sliver of humanity. He’s too eager to wipe out as many Mexicans as possible. Period.

Cuaron doesn’t entirely abandon politics once the movie gets under way. One immigrant character explains how she was forced to flee her homeland due to the violence in her community. She then adds, “if only they knew what things were like here,” as if every illegal immigrant will star down a Morgan-esque killer at some point in their U.S. journey.

FAST FACT: Jonas Cuaron made his feature film debut as a child in his father’s 1991 movie “Solo con tu pareja.”

Cuaron wisely keeps the dialogue to a minimum. Once the bullets start ricocheting around the desert sand, the story is purely a survival yarn.

The film’s score veers from traditional orchestration to a melange of white noise bursts. It sounds like a gadget that was left on too long and starts to malfunction. Given how spare the storytelling is, the score must fill the narrative gaps. It does just that.

HiT or Miss: “Desierto” could have been the most incendiary film of the year had it followed through on its open border premise. Instead, it drops the polemics to deliver a gut-wrenching survival story.