Here’s what the best movies about talk radio — “Talk Radio” being the gold standard — get right.

It’s what Marshall McLuhan called a “hot medium,” requiring the engagement of the listener/consumer at a level TV and film don’t. Voices matter. The words matter.

It’s a world with urgency built into it, an endless succession of moment by moment deadlines where every second is “money” and even the most laid-back practitioners (the somnambulists at NPR, and their podcast imitators) have an energy that can seem manic when you look behind the scenes.

“Dead air” — casual, undramatic silences — is a death sentence. No one “listening at home” will “stay tuned.”

The Eddie Marson talk radio thriller “Feedback” a couple of years back got most of these elements right. “On the Line,” the new Mel Gibson thriller about a “shock jock” held hostage, on the mike, by a threatening caller, gets most of them wrong.

It’s bad radio, and that makes for a very bad movie.

It feels off in ways obvious and also more slyly annoying. By the time we hear the fourth foreign accent with LA’s KLAT-FM staff — building guard to program director, Brits and Asians and Continentals, one and all — we’ve guessed that they filmed this thriller abroad. My guess was South Africa or Eastern Europe. No, writer-director Romuald Boulanger cast and shot this close to home, in Paris.

We never hear a commercial from this alleged commercial radio station, never get a sense that the real-time (ish) story is ticking over and tensing up. The host, Elvis Cooney (Gibson), is Imus-old and slow, spewing his low-energy patter into the cosmos with nothing that would keep a listener engaged in a Top Five market.

It’s no wonder his ratings are “flat as a crepe,” the program director (Frenchwoman Nadia Farès) complains, in the parlance of Paris. He’s making bad radio.

The movie? It never overcomes that unreality, never gets up a head of steam. And no amount of scripted surprises — all packed into the finale — can atone for that.

Elvis kisses his wife and five year-old daughter good night, checks into the high rise where the station is located, and we note how he doesn’t know the Anglo-Indian security guard and has no interest in learning how to pronounce his name.

“On the Line” is a midnight/all-night anything goes chat show, something Elvis has wearied of. We see how angry the guy who has the earlier time slot (Kevin Dillon) is over Elvis coveting “my show.”

A new, wet-behind-the-ears British engineer (mislabeled the “producer”) here, Dylan (William Moseley) sees what Elvis looks like “triggered,” as a part of his hazing ritual on the job. The much-younger call-screener, guest-booker and real producer Mary (Alia Seror-O’Neill) is in on the prank, and takes the “washed-up diaper wearing has-been” host’s sexist jokes with good humor.

What kind of audience might a no-holds-barred (lots of F-bombs and other profanity on the air) host attract?

“Nocturnal emitters,” Elvis labels them. But his callousness can bend towards kindness when he senses a caller is troubled. That would be “Gary,” who is “gonna do something really screwed up tonight.” Gary has a beef with somebody. “I’m gonna take out his whole family.”

And Elvis takes pains to talk him out of it. By the way, where’re you calling from, Gary?

“I’m at YOUR HOUSE!”

A kidnapping “game” with murderous blackmail, humiliation and execution is set in motion. It’s shockingly convoluted and stunningly dull.

Characters meander all over the high rise, threats are made and a couple of people are turned into corpses.

“Let’s call the police to save time!”

Naah, “I’ve dealt with kooks like this for 30 years,” and cracks about “We’ve gotta keep the cops kosher, right?” remind us that the star of the show’s in charge, and that the star of the movie was anti-Semitic before Kanye tried to make anti-Semitism cool.

The screenplay is laced with the phrase “I’m begging you,” with advice like “We have to hurry” which neither the characters nor the filmmakers listen to.

There’s little menace in the (mostly) unseen kidnapper’s voice, and Gibson never lets on that the stakes are as high as the story claims.

It’s a movie that demands we tune out long before it tries to “explain” away its shortcomings.

Gibson’s always given fair value, even in C-movies in his post-cancellation dotage. This one dogs along until the cheap cheat of an ending lands. And tries to land again.

But at least he and Dillon got a trip to Paris out of it.

Rating: R (Language Throughout|Some Violent Content)

Cast: Mel Gibson, Alia Seror-O’Neill, William Mosely, Nadia Farès and Kevin Dillon.

Credits: Scripted and directed by Romuald Boulanger. A Saban Films release.

Running time: 1:44