In “The Unbearable Weight of Massive Talent,” Nicolas Cage plays Nicolas Cage, a conceit we get used to in a matter of seconds, even as it turns into a gift that keeps on giving. There’s a reason we get used to it so quickly: Movies with a meta dimension have been with us for years — movies like “The Player,” where Robert Altman cast a galaxy of Hollywood stars as their real-life selves, or “Being John Malkovich,” where John Malkovich played John Malkovich, or “Adaptation,” where Cage played Charlie Kaufman, the screenwriter of the film we happened to be watching. Unlike those movies, “The Unbearable Weight of Massive Talent” isn’t a floridly ambitious pretzel-logic art film. It’s a commercial comedy that has a delirious good time poking fun at Nicolas Cage, celebrating everything that makes him Nicolas Cage — and, in the end, actually becoming a Nicolas Cage movie, which turns out to be both a cheesy thing and a special thing.

Tom Gormican, the director and co-writer of “Unbearable Weight,” knows all too well that when it comes to Nicolas Cage, you can’t separate the specialness from the cheese. That’s the source of Cage’s inside-out cool: that you’re laughing at him the very moment he leaves all subtlety and good taste behind, and he does it with so much shameless commitment and purple passion that our giggles fuse with something like awe.

Actors have onscreen lives and offscreen lives, and in most cases that’s all there is to it. But Nicolas Cage, in addition to having both those things, has a third life — as a meme, an unintentional tongue-in-cheek identity that has emerged from the mountains of outrageously over-the-top acting he’s done. Of all the actors of the last three or four decades who’ve been willing to squander their talent on what we call paycheck movies, Cage is the unabashed king (though Bruce Willis, in recent years, has given him a run for his easy money). And that says something about who he is. Each time Cage makes one of those films, like “Ghost Rider” or “Bangkok Dangerous” or “Mandy,” what you see on some level is a projection of his desperation — the fact that he’s a dude who needs the money this badly, or has simply fallen out of respectability and will take whatever role comes his way.

But you also see that Cage is addicted, on some squalid but weirdly innocent level of acting-as-exhibitionism, to doing movies that allow him to completely cut loose. Even when the film he’s starring in is trash, his need to act — his need to be Nicolas Cage — has given him a kind of kitsch purity.

In his way, Cage has become an ironic legend: the superhero of slumming. And the unique thing about him is that you can no longer separate the grade-Z Nicolas Cage movies from the grade-A Nicolas Cage movies. That’s because they share the DNA of his compulsion to express who he is by leaving all restraint behind. He first started doing that back in the ’80s, in prestige Hollywood films like “Peggy Sue Got Married” and “Moonstruck.” By the time he made “Wild at Heart,” in 1990, playing a kind of postmodern bad-boy Elvis, he seemed to be directing every line toward the peanut gallery, or maybe to the legend in his own mind. A Nic Cage Moment will be all about his eruption — that instant when he slides from normal acting into operatic overacting, as if the devil made him do it. What Cage’s fans know is that there’s a metaphysic to being Nicolas Cage, and it is this: Any actor who needs to act this much can only be satisfied when he’s acting…THIS MUCH.

“The Unbearable Weightiness of Massive Talent” opens with a canny portrait of Cage, wearing a beard that seems to signify bourbon-sozzled middle-aged depression, as a fallen Hollywood player who is no longer in line for the good roles. The portrait is fiction, of course, but it’s rooted in our highly detailed media perception of Cage. So it seems real. This Nic is a divorced dad who’s got a crummy relationship with his teenage daughter, Addy (Lily Sheen), because all he ever thinks about is his acting career. After a meeting with a prestige director at the Chateau Marmont, his hunger to land the role he’s up for is so intense that he offers to read for the part — and does, complete with bad Boston accent — right there in the parking driveway. At a therapy session with Addy, the two discuss how he made her watch “The Cabinet of Dr. Caligari” with him because it’s one of his favorite movies, never suspecting that his 21st-century daughter might not be so interested in a 100-year-old silent film with expressionist madman sets.

A fading star who’s a ruthless narcissist sounds like a cliché. But in Cage’s case the joke is that it’s the very fuel of his persona — his need to go over-the-top, because it’s all a way of seizing the attention he thinks he deserves. In the movie, Cage has conversations with himself in the form of a cooler, younger alter ego — a de-aged Nicolas Cage, in a swath of honey-blond hair and a shiny leather jacket, who tries to coax him into being the Cage he should be. The “real” Nic is riddled with self-doubt; the imaginary Nic is all teeth-flashing bravado. But, of course, that’s exactly who Cage has been in movies like “Con Air” and “Face/Off” and “Wild at Heart” and “National Treasure” — an actor who represses all doubt, and therefore seems heroic and ridiculous at the same moment.

After a spa meeting with his agent (Neil Patrick Harris), it becomes clear that the only thing Cage is being offered isn’t a movie. It’s a $1 million gig to travel to the Spanish coast of Mallorca and hang out with Javi Gutierrez (Pedro Pascal), a wealthy arms dealer, on his birthday. Since Cage owes 600 grand to the Sunset Tower Hotel, the West Hollywood spot where he’s been living for a year, he flies out to take the gig. Javi is a genial, flaked-out fan who has written his own script for Nic; he may also be a ruthless criminal. But either way, Javi believes in Nicolas Cage — in the myth of his flamboyant hyperbolic acting as a kind of mad-dog perfection. And so, of course, does Cage. They’re perfectly matched.

“The Unbearable Weight of Massive Talent” is at once a gently preposterous buddy movie; a poker-faced crime thriller in which Nic is coerced, by a couple of CIA agents (Tiffany Haddish and Ike Barinholtz), into spying on Javi, who they allege has kidnapped the daughter of the president of Catalonia; and a hall-of-mirrors romp in which the life of Nicolas Cage turns into a movie and then back again. Gormican stages it all with a witty instinct for how suspense can acquire comedy without losing its tension, but mostly he attunes every moment to Cage’s hangdog anxiety, and to the drama-queen dimension that allows him to oscillate between the “real” Nic Cage and the Cage of his dreams. As Nic and Javi become friends, the two drop acid (in a sequence of hilariously precise paranoia) and they goad each other into taking each moment and kicking it up into their very own “movie.” As Cage’s ex-wife (Sharon Horgan), along with Addy, shows up to save him, and the real criminals come to the fore, the entire situation begins to coax Nicolas Cage into becoming…Nicolas Cage. It’s his destiny.

The film is speckled with clips from Nicolas Cage movies, quotes and gestures form Nicolas Cage movies, and a visit to Javi’s museum of Nicolas Cage memorabilia. Yet what makes “The Unbearable Weight of Massive Talent” a joke thriller with an exuberant resonance is that its true subject is the magic of movies. It’s about how an actor like Cage can mean so much to us because, in the very extremity of his flamboyance, he’s acting out something that means so much to him. He’s not suffering for his art, but he’s doing what may be the next best thing: showing off for it.