“Locke” is one of the more unusual and brilliant movies to open in theaters this year. That didn’t stop two different couples from walking out in the middle of the local screening a couple of weeks ago.

You have to know what you’re getting into here and you can bet your petunias they had no idea what they were going to see when they sat down and faced the screen.

This is a stunt, just like its extraordinary cousin Rodrigo Cortes’ virtuoso piece “Buried” from 2010. What you’re watching in this one is a man driving to London at night in his BMW and talking on the phone installed in his car.

That’s it. That’s all that happens – which is, of course, many people’s idea of nothing at all. “Godzilla,” this isn’t. Not “X-Men” either.

What happened in the extraordinary “Buried” is that a man woke up buried alive in a coffin in Iraq and bewailed his plight on his cellphone. That phone and a couple of glo-sticks provide the only ostensible illumination for the entire film. That’s all that separates the coffin he’s in from total darkness. It was just actor Ryan Reynolds in a wildly surprising tour de force talking to people on his cellphone.

It’s less surprising to have actor Tom Hardy doing the one-man performance on camera here. All he’s doing as Ivan Locke is driving, talking to people on the car phone and trying to keep his entire life from collapsing into chaos. Sometimes he’s forced to consult a job folder which he forgot to leave in an office drawer.

Locke is a good man by almost any definition. But he made one mistake – one minor drink-fueled errancy in an otherwise exemplary and immensely competent life. And because of it, his life is falling apart while he drives to London on an emotional errand he refuses to avoid.

Because of his insistence on making the trip, he has to try fanatically and desperately to keep his job, his marriage and his kids, even while knowing there’s a possibility he’ll lose every one of them.

He is paying a terrible price on the phone for being an ethical man, but it’s all he’s able to do. So he has to explain anyway to everyone he talks to. It’s a straight road he seems to be on – morally it is anyway.

Both Hardy and the actors and actresses heard on the phone are completely equal to all of this.

I suspect that the walkouts (as Lenny Bruce, among many other comics, used to call them proudly) were caused by the film’s entirely startling way of immersing you in the micro-details of what a job foreman on a gigantic construction project actually has to do. Ivan has been occupationally contracted to do them all which means in his moral universe, he must make sure they’re all done perfectly.

You’ll have almost no intrinsic interest in any of the job details, but you’re not really supposed to. It’s Ivan’s unwavering rectitude despite the ambiguities of chance and the slippery moral character of others that you’re listening to. It’s the emotional subtext that remains gripping throughout.

As I said, though, if you’re not prepared for what this movie is, the seeming eccentricity of the cinematic stunt may require more patience than you have even though the film is a very taut 85 minutes long.

It ends satisfyingly even though none of the plot questions have been answered in the slightest.

As I said, this is a very unusual movie. The writer is Steven Knight, who previously wrote David Cronenberg’s “Dirty Pretty Things” among others on a wildly varied list. Kudos to everyone involved in making it so well.

Obviously, Hardy – most famous as the villain Bane in “The Dark Knight Rises” – carries the movie on his back and never lets it slip, not once.