The first really exciting moment of my day with Dwayne Johnson was when he showed me the evolution of his punch. We were talking in a room near his kitchen. Johnson was barefoot, legs stretched out on his couch. He wore black jeans and a black Willie Nelson T-shirt, the sleeves of which were working extremely hard to fit around his biceps. Hawaiian music (Don Ho Radio) played from a Bluetooth speaker. I was telling Johnson, apologetically, that I wasn’t really a pro wrestling fan — that the last wrestler I could remember liking was a guy from the 1990s called Razor Ramon, a sneering villain with wet curly hair who used to throw his toothpick at kids in the crowd.

“I liked that guy too,” Johnson said — and this sent a little scrap of research rattling loose in my mind and tumbling out of my mouth: I had read somewhere that Johnson, early in his career, studied and copied Razor Ramon’s punch.

“Wow!” Johnson said.

This factoid made him happy, and so he unleashed his famous smile, the shining white charisma-bomb that sometimes seems like the whole reason movie screens were invented, and also the reason GIFs were invented, and also (I can say now, having seen it in person) the reason smiling in person was invented. It is a smile that makes you feel as if the sun is setting over an undiscovered tropical beach on which 10,000 baby sea turtles are about to hatch.

“Wow!” he said again.

And, smiling that smile, Johnson told me the story of his punch. Back in the infancy of his wrestling career, before he was this multimedia phenomenon known as the Rock — before he could whip up whole arenas by raising a single eyebrow, before he hosted “Saturday Night Live” five times, before he got the word “smackdown” added to the Merriam-Webster Dictionary or became People Magazine’s “Sexiest Man Alive” or found himself seriously courted by political parties to run for president — all the way back in 1996, Johnson was still a newbie performing under the name Flex Kavana. (Do not ask.) One day, he got the opportunity of his dreams: a tryout match for the what was then the World Wrestling Federation. It went fairly well, and backstage, afterward, everyone was congratulating him.

Then Pat Patterson shuffled over. Patterson was a salty old wrestling veteran, a power player in the industry. Gravelly voice. Big slab of a face. Cigarette in one hand.

“Good job,” he said.

“Thank you,” Johnson said.

“Your punches,” Patterson said — and the statement just hung there, unexplained, in a cloud of smoke.

“Yeah?” Johnson said.

Patterson poured out a small flood of expletives.

“No good?” Johnson said.

“Horrible,” Patterson said. Right there, he gave Johnson a little master class in the spectacle of hand-to-hand combat. You have to throw a great punch, he said. It’s the basic building block of the whole show. The delicate ecosystem of pro wrestling — the fakery and reality, the soap opera and the street fight — all of it rests on the foundation of a punch that, even though everyone knows it’s fake, also seems to be doing real damage.

Johnson has told this story before, and at this point I interrupted. “Can you show me the difference?” I said.

He paused. “Show you?” he said. “Like, right now?” And before I could even answer, he was leaping up off his couch. He moved very fast, with big easy strength, like a tree branch in a strong wind.

“OK,” Johnson said. He stood lightly on his feet, knees bent and ready, bouncing. “So — what’s the difference?”

I clambered out of my own chair to see — and instantly Johnson sort of teleported past the coffee table and reappeared right in my face, squared up, ready to punch.

Suddenly, I found myself with a very interesting view of Dwayne Johnson — the kind of view usually reserved for John Cena or Vin Diesel or whatever C.G.I. creature he is punching at work that day. Mostly what I saw were Johnson’s big fists: serious knuckly danger-cubes. Way off in the distance, peeking over, loomed the round top of his bald head. His heavy-lidded eyes were trained on my face.

“So,” Johnson said, fistily. “There are certain punches guys will throw.”

And like a truck blowing through an intersection, his giant right hand came flying at my forehead — then froze. “Boom,” he said. I don’t know if it stopped two inches from my face or two millimeters, just that it hung there for a beat, motionless, as if someone had unplugged it. Then it pulled back.

“Or sometimes,” Johnson said — and his fist whipped at me again, this time at my cheek — “guys will throw like this: Boom.”

Over and over, Johnson sent his menacing knuckles flying at different targets on my face: boom, boom, boom. He showed me how a really hacky wrestler will oversell a punch by hopping off the ground, stomping both feet — a con you can see from the back of the arena. (Johnson hopped and stomped; the floor rumbled.) I just stood there, perfectly still; with every punch, I felt a deepening sense of peace. I understood with total certainty that Johnson was never going to hit me. I could feel the precision in his motion — a full-body wisdom, fluency, expertise. This man, I suddenly realized, was an artist.

On screens — in car chases and in wrestling rings — things tend to look easy for Johnson. He is a sort of human cartoon. But that’s all just an elaborate trick. Behind the scenes, he is technical, obsessive, studious. He loves details. After Pat Patterson critiqued his punch, Johnson went down to wrestling’s version of the minor leagues, where he performed for $40 a night in barns, carnivals, flea markets, parking lots. On his off nights, he studied VHS tapes of wrestling’s best punchers — especially Razor Ramon. Because that punch was something else entirely. Johnson watched it in slow-motion, over and over, breaking down its component parts, trying to infuse it into his own limbs.

Almost 30 years later, standing next to his coffee table, Johnson presented me with Razor Ramon’s punch. “It was all this beautiful body push,” he said — and he flew across the room, twisting, upper and lower body torqued, arms spread wide, then surged forward, fluid and fast, his whole trunk helicoptering around, right hand whipping into a vicious punch, left hand snapping down toward the floor, and there was a crash, and the whole room shook.

Johnson was correct. This was a whole different species of movement. It was devastating but elegant. Gentle but deadly. I told him it looked like tai chi.

Johnson demonstrated that punch, with obvious joy, again and again, explaining all its little subtleties, the multiple sleights of hand: the way the right fist opens into a slap just as it meets your opponent’s jaw, then closes before the crowd can see it; the way the left hand slams against the puncher’s own left thigh, imperceptibly, creating a noise people think is the punch.

Learning it taught him a crucial lesson. Pro wrestling is, in large part, the art of dramatizing pain: the theatrics of dishing it out, absorbing it, selling it. Wrestlers gasp, wince, crawl, roll, clutch their backs, slap the floor. Nothing about this can be done casually. Pain, even fake pain, is an elemental, almost sacred thing. You can’t disrespect it. To do it well, you have to use your whole self.

I do not need to introduce you to Dwayne “Dwayne ‘the Rock’ Johnson” Johnson. He is basically as famous as a person can get. Johnson once stood on the field, just before kickoff, to introduce the Super Bowl. That’s the kind of popularity we’re talking about — he introduces the Super Bowl the way the rest of us might introduce a cousin who is visiting for the summer. When Johnson appears on your screen, you know exactly what you’re getting: wisecracks and weapons and chase scenes and C.G.I. animals. He is pure cinematic sunshine, appearing at regular intervals to beam down rays of positivity and entertainment and good old-fashioned mainstream popcorn fun.

But Johnson’s new movie, “The Smashing Machine,” is not like any of that. It is not a feel-good romp or lighthearted reboot. It is, as its title suggests, intense and bloody. There is indeed a lot of smashing: smashed faces, knees, ears, doors, lamps, bottles, souls.

The film tells the story of Mark Kerr, a.k.a. the Smashing Machine — a name that, for most of us, has approximately 0.000000001 percent of the name-recognition of the Rock. (I might have left out a few zeros.) But Kerr is a fascinating character. In the late 1990s, when the Ultimate Fighting Championship was still new, when it was being denounced in the Senate as “human cockfighting,” Kerr had a brief but terrifying run of dominance. He was so strong that his muscles looked exponential. He looked like a sentient pile of cantaloupes. And his fights were electrically scary. Kerr would launch himself at an opponent’s legs, take him down, then jackhammer the guy’s face with all the hardest parts of his body — fists, knees, forehead — until the fight was stopped. “Ground and pound,” people called it. He knocked out one fighter in 19 seconds. Another he forced to quit by drilling his chin into the guy’s eye socket.

Kerr’s story was first told, grippingly, in a 2002 documentary also called “The Smashing Machine.” (This would become the source material for Johnson’s film.) The documentary’s director, John Hyams, wove raw, intimate footage into a sad existentialist portrait. The film shows Kerr dominating opponents and basking in the roar of huge crowds. But it also shows him suffering in the aftermath: wincing at the touch of a doctor, arguing with his volatile girlfriend, Dawn, weeping in a hospital bed after an overdose of painkillers. In fighting circles, it was must-watch stuff, an instant cult classic. On one level, it was a cautionary tale about the fall of a seemingly invincible force. But it was more than that. Kerr’s story articulated things about violence and pain and loneliness that usually remained unspoken, especially in the hypermasculine world of fighting.

One of the documentary’s fans was Dwayne Johnson. When it came out, in 2002, his career was already ascending, at a very steep angle, from wrestling superstardom toward the highest altitudes of Hollywood. But when Johnson sat down to watch “The Smashing Machine,” it brought him instantly back down to earth. He felt as if he were watching an alternate version of his own life. Not so long before, when Johnson’s pro wrestling career was floundering, he had briefly considered switching over to mixed martial arts — and he had discussed the idea with, of all people, Mark Kerr. (They worked out for a while at the same Gold’s Gym.) Now, captured mercilessly on film, here it was: the road not taken. As the years passed and Johnson’s film career exploded, as he made “Fast & Furious” sequels with increasingly large numbers (5, 6, 7, 8, X) and also a reboot of “Jumanji” followed by a sequel to the reboot of “Jumanji,” the Rock couldn’t stop thinking about the Smashing Machine.

What really fascinated him was the man himself, Mark Kerr — the soft beating heart at the center of all that violence. He was an irresistible paradox: a sensitive soul who earned his living by crushing people. In the film, Kerr speaks openly, thoughtfully and at great length about suffering, his own and everyone else’s. He talks about the death of his mother, his descent into addiction, his ragingly codependent relationship. Kerr’s speaking voice is sweetly Midwestern; it sounds like a pair of cupped hands picking up a baby bird. In that tender tone, he explains that he never really wanted to fight, that he doesn’t enjoy hurting people — that in fact right before his first match he was struggling not to vomit. (According to his trainer, Kerr refused to come out of the locker room until he was informed that, if he didn’t, the Brazilian crowd would probably riot.) In other words, Kerr is what is known as a gentle giant. He’s like if the Incredible Hulk opened his mouth to reveal that he was actually Mr. Rogers.

All of this resonated with the Rock. His own career, Johnson knew, had been ridiculously lucky — he really did understand that, you do not have to lecture him about his luck, he will spend all day beaming out gratitude to the ancestors and allies and brothers and sisters and fans who made it possible. But the thing is, he had started to feel a little carried away by his own success. The studio pressure, the side businesses, the meetings, the requests, the smile, the charisma. He was the same person he’d always been, but he had a very different relationship to the world. He was so famous he couldn’t really go outside. Again, he was not complaining! And yet there was that old Hollywood paradox: On some deep, human level he also felt unseen, unknown, constrained. A few years ago, Johnson found himself asking, frequently: Am I actually doing what I want? Or am I just doing what the people around me want?

This is when he became obsessed, for real, with “The Smashing Machine.” Johnson dreamed of taking the classic documentary and dramatizing it, blasting it out to the biggest audience possible. He wanted everyone on earth to appreciate the unexpected magic of Mark Kerr. And Johnson fantasized about playing Kerr himself — finding a way to embody this flawed, musclebound saint, the man of sorrows who swallowed so much pain it nearly killed him.

Johnson knew that “The Smashing Machine” would require a new kind of performance: not his usual charm and lightness but real pain, the sort of agony you can draw only from the reservoirs of your own life. The role would allow Johnson to express unexpressed parts of himself. He felt desperately ready to do so.

Scheduling an interview with the Rock feels like trying to set up a coffee date with the king of England. Over months of back and forth with Johnson’s representatives, I got a sense that the pressure on his time is geological — that every moment is getting crushed from every direction all at once. Large windows on the calendar gradually narrowed until, toward the end of the summer, we had a date. “D.J. would love to host you at his farm in Georgia,” I read. “He’d love to introduce you to his bull that he’s raised on the farm.” I received a detailed itinerary, along with instructions to text his assistants when I reached the front gate.

So I was surprised, when I arrived, to find that Johnson was alone. He drove out on a four-wheeler and opened the gate himself. Then he led me up the road toward his house, using a series of little hand gestures that made me feel as if we were an elite two-man squadron infiltrating enemy territory.

Very quickly, we settled into a room off his kitchen and tumbled into a conversation about the history of Hawaii. Talking to Johnson, I discovered, is a fully immersive experience. He is willing to go basically anywhere, and he will carry you right along with him. In our time together, I hit only one roadblock: Deep into the night, when I tried to bring up politics, Johnson raised his glass and clinked it on mine. “Sam, brother, you’ve asked a lot of great questions today,” he said. “What’s your next one?”

As a conversational partner, Johnson is almost hilariously curious. He was constantly pausing his own answers to reflect questions back at me. He asked about my childhood, my siblings, my writing, my parents’ divorce, the death of my father. (Did you know that would be the last time you saw him? Do you think he knew? What was his name? Do you miss him?) He was fascinated when I mentioned tai chi. (How is that related to meditation? What kind of shoes do you wear? Has it changed your life?)

When you answer, Johnson listens hard, strenuously, athletically — as if he is squatting the weight of your answer with the bulging quads of his soul. When things start to get really revealing, when he feels what you are saying, you will begin to hear big rumbling noises: a deep seismic “MMMMMMMMMM” rolling your way from across the room. It sounds like a huge creature slumbering — like a dragon that is having a very meaningful dream about you.

We were scheduled to talk for four hours but ended up talking for more than eight. I not only met Johnson’s bull — we fed it caramel-flavored snacks over a fence — but also went out with Johnson to a steakhouse where, at one point, a whole 16th-birthday party tried to break into our private back room. And the conversation did not end there. Beginning the morning after our interview, I started to receive voice memos and videos from Johnson: thoughts, stories, further questions. At the end of August, when I dropped my son off at college, Johnson sent a Spotify link (Sawyer Brown’s 1991 song “The Walk”) along with a message that read like a soulful haiku:

To listen to later

You and I both have taken “the walk”

Now it’s your son’s time

Hour after hour, text after text, the topic Johnson and I returned to was pain. This is the true subject of “The Smashing Machine.” It marinates the viewer in pain: the ways we cause it, absorb it, express it, deny it. After I saw the film, I found myself thinking obsessively about the subject. I started to ask everyone I ran into a simple question: What’s the worst pain you’ve ever felt? People would answer with nightmarish stories about scorpion bites, bike accidents, bones sawed in half. Or moving stories about childbirth, parents with Alzheimer’s, euthanized pets, drug addiction. Everyone had something. To my surprise, the conversations rarely turned out to be depressing — they were deep, intense, funny, energizing and often, paradoxically, uplifting.

In Johnson’s living room, after his elaborate punching demonstration, once we’d settled into our seats again, I decided to ask him my question. “What’s the worst pain you’ve ever felt?” I said.

Johnson went silent.

Ice clinked in his glass.

“Wow,” he said, and this time his voice was soft, and he didn’t flash the famous smile.

I had some guesses about what he might say. Over the course of Johnson’s career, he has been fairly open about his life. As the Hawaiian music filled the room, as he continued to think, I reviewed in my mind what I already knew about the landscape of Dwayne Johnson’s pain. There were a few obvious peaks. During his childhood, his family moved a lot — Texas, Georgia, Oregon, California, North Carolina, Connecticut, Florida, Hawaii, New Zealand, Pennsylvania, Tennessee — and he was constantly being yanked from one school to another. This made it hard to keep friends. There were fistfights, brushes with the law. In high school, Johnson became a football star, earning a full scholarship to the University of Miami, and he seemed plausibly on track for a career in the N.F.L. But then, just before his freshman season, in a practice drill, a teammate drove him into the ground, destroying his left shoulder. This not only required surgery and ended his season; it also sent him into a serious depression. His football dreams never fully recovered.

In the decades since, there have been plenty more agonies and disappointments: new bouts of depression, a divorce from his first wife, high-stakes projects that failed. This is to say nothing of Johnson’s many years in pro wrestling — a theater of suffering in which the pain often crosses over to reality. While traipsing around in spandex, Johnson has torn up his knee, snapped his Achilles, bruised his lung so badly he coughed up blood and been blasted across the ring by Stone Cold Steve Austin’s fire hose of beer. In a single match against John Cena, he tore his quadriceps and his adductor clear off his pelvis, as well as lacerating his abdominal wall in so many places that he ended up in emergency surgery.

Finally, after a long silence, Johnson answered my question.

“The worst pain I’ve ever felt,” he said, and then he paused again. And he told me a story about his father.

I’m going to pause here, briefly, to introduce you to the phenomenon of Rocky Johnson. It is impossible to understand Dwayne Johnson without him. Rocky Johnson is less a father than he is some kind of over-the-top mythological origin story — a prequel in which the writers took everything way, way, way too far.

Let’s start with this: Rocky Johnson came from pain. He was born in Nova Scotia, to a family that arrived there, generations earlier, after fleeing slavery in the American South. His birth name was Wayde Bowles. (“Wayde” — almost, but not quite, an anagram of “Dwayne.”) Wayde’s own father died just before he turned 13, and within months of that tragic loss, his mother kicked him out of the house. (Her new boyfriend got drunk, the story goes, and peed all over their Christmas turkey — so Wayde knocked him out with a shovel.) Dead broke, with nowhere to live, Dwayne’s father hitchhiked to Toronto, where he worked odd jobs to survive. He took up boxing, eventually getting good enough to spar with George Foreman and Muhammad Ali. That led him to his true passion: pro wrestling. He chose the ring name Rocky Johnson, then changed his legal name to match it. He was a figure of pure self-invention, a victory of fantasy over reality. Rocky Johnson had not only survived; he had built a new self out of nothing.

What that new self did was wrestle. In the 1960s and ’70s, Johnson was a pioneer: a trailblazing Black star who performed across North America and beyond. Pro wrestling, back then, was not a glamorous career. The schedule was brutal, and the money was bad. The audience wasn’t yet national — it was split up into little fiefs, so wrestlers would move among them like circus performers, bringing fresh shows to different crowds. The circuit flung Johnson coast to coast, back and forth — including, constantly, into the American South, where Black wrestlers were still asked to perform demeaning stereotypes: speaking in dialect, eating watermelon, allowing themselves to be whipped. Johnson refused all that. In the ring, he insisted on playing the good guy — the “babyface.” He was disciplined, serious, a true athlete — one of the first pro wrestlers to have a bodybuilder’s physique.

Dwayne often describes his relationship with his father as “complicated.” But that poor word is not nearly strong enough. As a baby, then a toddler, then a teenager, Dwayne sat ringside to watch Rocky, who was built like a superhero, fling cartoonish wrestling villains around in front of adoring crowds. There is W.W.E. video footage of this: young Dwayne, doe-eyed, watching the man he worshiped play out this theatrics of pain.

Outside the ring, meanwhile, Rocky didn’t have a lot of spare time. He woke up early and went to the gym. He drove long hours to get to his matches. His job could pull him away for days or weeks. At around 5 years old, Dwayne started tagging along on his father’s workouts. He wasn’t allowed to touch any weights; he would just sit in the corner and watch Rocky lift — pumping up those famous muscles, one by one. When Dwayne got a little older, Rocky would take him over to a wrestling mat afterward to show him some moves. That, along with impromptu fishing sessions during long drives, was the main way they spent time together.

Johnson’s mother, Ata Maivia, also came from a wrestling family. Her mother, Lia, was a powerful promoter; her father was the revered Samoan wrestler High Chief Peter Maivia. She understood the lifestyle. But her marriage to Rocky was volatile. Their arguments were explosive. Sometimes they lived apart.

It was a confusing way to grow up — a swirl of reality and fiction. To understand it all, it helps to know a classic wrestling concept called “living the gimmick.” Rocky Johnson was a master of it. His son remembers wondering, as a child, why his father always had fancy cars — Lincolns, Cadillacs — but drove them home to motels and trailer parks and dingy basement apartments. That was living the gimmick. For Rocky, illusion was a survival mechanism. He could talk his way out of, and then back into, any kind of trouble. Johnson told me that his father never really learned how to write — he drew letters slowly, painstakingly, in big rudimentary shapes. And yet his signature was flawless: elegant and flowing, like the signature of a king. Even his physique was partly a show. His father had a huge upper body, Johnson says — he could bench press more than 500 pounds — but he completely ignored his legs. “Open up ‘skipped leg day’ in the dictionary,” he told me. “There’s my dad with a big smile.”

“The worst pain I’ve ever felt,” Johnson said — and he paused. “The worst pain I’ve ever felt was when we were evicted from Hawaii and I was sent to Nashville to live with my dad.”

This happened when he was 15. Dwayne and his mother were living in a small apartment in Honolulu. Rocky was off wrestling in Tennessee. The marriage was bad enough that, in some ways, it was a relief when his parents were apart. His father wasn’t physically abusive, Johnson says, but the fights were huge and scarring. Objects got thrown. Unspeakable words got spoken. From age 13 on, Johnson considered himself the primary man in his mother’s life. He was good at listening, helping, anticipating her needs.

One day, in Honolulu, they came back from the grocery store to find an eviction notice on the apartment door. Johnson remembers his mother just standing there, staring — then bursting into tears. Telling the story, Johnson teared up himself. “It hurt my heart,” he told me. “It hurt my heart to see my mom like that.”

Once Ata had gathered herself, she called Rocky. She told him that, while she tied up loose ends in Hawaii, she wanted to send Dwayne out to Nashville. In the meantime, she said, she would ship the car to the mainland, then drive out with all their belongings. Then they could try to live together as a family.

“No problem,” Rocky said. “I’ve got an apartment.”

But Rocky, as always, was living the gimmick. When Dwayne, landed in Nashville, his father wasn’t there. Instead, he met a guy named Bob. Bob drove Dwayne to a cheap motel, where he knocked on a door and introduced him to a guy named Bruno. This, Bob said, is where you’ll be living.

That rejection hit Dwayne like a flying drop-kick. It added a new layer of pain to the initial pain of the eviction. He says he intuited, immediately, what was going on: His father was almost certainly living with another woman. This pain had implications: Soon his mother would be on her way, which meant more pain was coming up the road. “My heart hurts when I think about that,” he said. “The pain that my mom was driving with. Like: What is my life now? That whole time.”

And Ata still had no idea. She was making this road trip, all alone, in an extremely impractical car: a two-door red Ford Thunderbird. Rocky had bought it just before his career fell off a cliff, and now it was crammed with all their belongings, roaring from San Francisco to Nashville and into the parking lot of that crappy motel.

Ata had been led to believe that she was driving to her husband’s apartment. Instead, she was greeted by Bruno. (Bruno turned out to be great, by the way, a lifelong friend of Dwayne’s — Dwayne recently bought him a truck. Still, not the point.) Dwayne was there too, as was Rocky, inexplicably driving a car with Illinois plates.

Johnson says that his mother, too, understood everything immediately. “That was it,” he said. “Within five minutes, it all just. … ” His voice trailed off. “It wasn’t even an explosion,” he said. “It was just — a collapse.”

His father started telling obvious lies. His mother got ominously quiet. Later, when Rocky wouldn’t stop talking in circles, his son walked over and whispered: “You should give her a hug.” But the hug didn’t fix anything. That nightmare of a day continued to spiral, ending in a terrifying moment when Ata stepped out of Rocky’s car and walked straight into freeway traffic. Cars swerved and honked. Dwayne pulled her back. The look on her face, he told me, is something he had never seen. She was gone, he said.

Somehow, Johnson’s parents stayed together. (They wouldn’t divorce until many years later, in 2006.)

Dwayne Johnson, meanwhile, got busy embarking upon the journey of becoming Dwayne Johnson. There were still a few bumps along the road. When his football career ended in total humiliation (he got cut from a practice squad in the Canadian Football League), he ended up moving back in with his parents, where he spent many aimless days depression-scrubbing their Florida apartment. Then he announced a new life plan: He wanted to be a pro wrestler.

Rocky, as you might guess, hated this idea. It’s hard to say if he was being protective (wrestling was a hard life) or just selfish (wrestling was his hard life). Either way, it kicked off an apocalyptic argument, and somewhere in all the screaming and crying and crashing, Dwayne’s father uttered a sentence that would stick with him for the rest of his life: “What do you think you possibly have to offer?”

The answer turned out to be: quite a lot, actually. A titanic boatload, thank you very much. By some measures — revenue, catchphrases, crossover success, eyebrow — you could argue that Dwayne “the Rock” Johnson had more to offer than anyone else in the whole long history of wrestling.

After a shaky start during which the W.W.F. tried to sell him as a generic babyface named Rocky Maivia (the combined names of his father and grandfather) — after getting showered with boos and chants of “Rocky sucks,” after beginning to think that maybe his wrestling career was a bad idea after all, after a knee injury — Johnson came back reborn, almost overnight, as the Rock: an arrogant villain who referred to himself in the third person and trash-talked everyone on earth. The Rock had long sideburns and cool finishing moves (the Rock Bottom, the People’s Elbow), and he could go boot to boot with all the other stars (Austin, Triple H, Mankind) of the late 1990s, a wildly popular period still remembered as the Attitude Era.

The Rock’s real superpower was crowd work. His connection to the audience was revolutionary. The wrestling became secondary — a backdrop for his skits and speeches and singalongs. His catchphrases (“If you can smell what the Rock is cookin’”) were so popular that the crowd would finish them for him. He was a ratings machine.

Johnson rode that momentum right into a Hollywood career. In 2001, his brief cameo in “The Mummy Returns” was such a hit with test audiences that, before the film was even released, the studio gave him his own spinoff, “The Scorpion King.” Soon he became one of the industry’s most bankable stars. When “The Fast and the Furious” franchise started to go stale, they trucked in the Rock to pick things back up.

As you might imagine, Rocky Johnson’s relationship to his son’s wild success was exquisitely complex — a bitter mix of pride, jealousy, ownership, resentment. Dwayne Johnson told me that his father always kept a little joke in his back pocket to put him in his place. Whenever he overheard someone complimenting his son — about wrestling, movies, business, whatever — Rocky would jump in.

“I taught him everything he knows,” he would say — and then, after a beat, when he was sure he had everyone’s attention: “But I didn’t teach him everything I know.”

Johnson still seems to wince a little when he says this.

For the first time in his film career, Johnson has been asked to draw on all of this pain. “The Smashing Machine” is emotionally brutal — a slugfest in which Johnson’s most frequent sparring partner is Emily Blunt, the English actor who plays Mark Kerr’s girlfriend, Dawn. In real life, Blunt and Johnson are close friends. They first met in 2018, when they starred together in the movie “Jungle Cruise” — a $200 million, C.G.I.-heavy, family-friendly action-adventure adaptation of the classic Disneyland ride. Blunt arrived on the set expecting to meet the Rock, the action hero: audacious, invincible, grinning.

Instead, she met someone else. Johnson was introverted and curious. He and Blunt hit it off. Soon they were talking for hours. They bonded so deeply that they often refer to each other, publicly, as best friends. “I mean, he’s really a magical person,” Blunt told me.

But that magic was also a source of frustration to her, because so little of it was allowed to come through in his work. Blunt could see how much of Johnson’s public persona was a performance, a character he invented to survive. And that character seemed to have taken over his whole career.

Johnson had heard this critique before, and he had a standard answer. Sure, he would say, some actors tear their guts out in their films, and I respect it. But not me. I’ll work through my private stuff in private. I just want to give people a good show. The audience comes first.

“I’ve given him [expletive] for years about this ‘audience first’ stuff,” Blunt told me. In her mind, the way to really serve an audience was to offer them your whole self — the big, joyful, painful mess of being a human in a difficult world. “This is audience first!” she would tell Johnson.

By this definition, with “The Smashing Machine,” Johnson has finally put the audience first. The film was written and directed by Benny Safdie, who (along with his brother, Josh) is known for edgy, experimental projects that blend fiction and reality. Safdie films often use artsy stunt casting: “Good Time” features Robert Pattinson, the English “Twilight” hunk, as a greasy New York bank robber; “Uncut Gems” features Adam Sandler as a white-knuckle gambling addict. But Dwayne “the Rock” Johnson is a whole different mountain of muscles. Johnson making a film with Benny Safdie is like Taylor Swift making an album with Björk.

Safdie’s version of “The Smashing Machine” recreates whole scenes from that original 2002 documentary — but dramatized and expanded, with strange extra touches thrown in. It adds dialogue and scenes no documentary crew could have captured. The result feels less like a normal sports biopic than like looking through a kaleidoscope while 10 sweaty men take turns punching you in the heart. The film is a wild collage of tones and performances. There are claustrophobic fight sequences with corny ringside commentary. There are long tender moments between men with such bad cauliflower ear they look like the BFG. There is a Japanese journalist in fingerless gloves who seems to have escaped from a David Lynch movie. There is enough jazz percussion to ruin every open-mic night in America.

When Johnson first approached him, Safdie didn’t know the story of Mark Kerr. But he quickly became obsessed. Kerr, he told me, struck him as “one of the most cinematic characters you could possibly have.” He was like a super-jacked version of George Bailey from “It’s a Wonderful Life”: a decent man who passes through terrible torment to reach a new understanding of his existence. Safdie saw Kerr as a vehicle for radical empathy; he asked himself, “What are the situations we could put him in to help the world to understand itself better?”

The film’s main event is Johnson’s performance. It required him to become Mark Kerr. As always, Johnson took the challenge extremely seriously. He had to sculpt his body into a whole different shape. Johnson, famously, has always been huge, but his thickness here is unbelievable. Each of his thighs should probably be listed separately in the final credits. Also, he changed the way he moves. Kerr, Johnson told me, carries his weight up high, concentrated in his shoulders. Johnson learned to stand like that, too, and to walk leaning forward slightly, as if he has been italicized. In one scene, Johnson was being filmed from behind, and Safdie noticed him starting to shift angles, performing in reverse. “I was like: This is amazing,” Safdie told me. “The guy is acting with the muscles of his back.”

Then, crucially, there is Kerr’s voice — that distinctive Midwestern golly-gee lullaby. Johnson worked with a voice coach, who taught him to speak gently, softly, from the bottom of his chin. (Johnson’s own speaking voice rumbles all the way up from the ground.) Johnson practiced this constantly, until he could toggle easily between his own voice and Kerr’s. He would send Safdie voice memos in character. “And I was like: Oh, this is going to work,” Safdie said.

But the most jarring transformation is Johnson’s face. It is one of the most valuable properties on the planet. And yet here it is defamiliarized, so you’re never quite sure whom you’re looking at. Johnson says this required hours in the makeup chair every day. There were 21 different prosthetics. (This was the work of Kazu Hiro, the Oscar-winning makeup artist.) Early on, Safdie decided that he didn’t want Johnson to look exactly like Kerr; he wanted that famous face to shine through, creating an eerie combination. The movie leaves you sitting in an uncanny valley between Dwayne Johnson and Mark Kerr, winning and losing, violence and healing.

But the hardest part of Johnson’s transformation was emotional. Right before they started filming, Blunt asked him if he was scared.

“I’m good,” he said.

“That’s not what I asked,” she said.

In that moment, Johnson told me, he realized he was terrified. This film was almost dangerously important to him. He had been fantasizing about it for so many years. Now here he was, on set, about to make it real. What if he couldn’t pull it off? What if he wasn’t that kind of actor? What if he embarrassed himself — or, even worse, embarrassed Kerr, a man he had come to love?

“I felt that he was maybe going underground a little bit,” Blunt told me. “And I just got the sense that maybe he was scared. Because I was scared. And I think maybe D.J. has avoided naming that. Because he had to be so resilient, from such a young age — the hero, the spine to keep everybody upright.”

Johnson agrees. “I didn’t identify it,” he told me. “I didn’t know. I didn’t label it.” As soon as he did label it, he started to see fear all over the place, including behind that old line about his film career: audience first. “I was just scared to do it,” he said. “That’s the truth.” He always believed he had been serving his audience. Now he realized he had just been living the gimmick.

I asked Johnson if he remembered the last time he talked to his father.

“I do,” he said. “Yeah.” Another long silence. “And it hurts.”

Their last conversation was a fight. A huge one — the biggest since that blowout, 25 years earlier, when Johnson first announced that he wanted to be a wrestler.

This fight was over a book. His father had just published his autobiography, “Soulman: The Rocky Johnson Story.” It was 2019, and Dwayne was now immeasurably famous. In addition to getting his story out, Rocky was also trying to cash in. Johnson says he was fine with that. But he also braced himself. Because he knew his father.

Sure enough, the book was full of surprises. The first thing Dwayne Johnson discovered was that he, himself, had written the foreword. Except he hadn’t. None of the words were his. The rest of the book was equally creative. “Growing up with my dad,” Johnson told me, “I know the truth to all these stories. And they’re not in this book. If the truth is blue, this story is red.”

Johnson could forgive all that. He was used to it. But then he reached a series of quotes, attributed to him, about how much he owed his father. All his success. Not just the wrestling but the TV shows, the movies — everything.

Johnson was shocked, hurt, angry. He thought about all his decades of work, and about all the other people who helped him and worked alongside him. Now here came Rocky, pretending to speak in Dwayne’s voice, claiming it all as his own.

“It just completely crossed the line,” Johnson said. “It goes back to the attention, and the narcissism.”

In the middle of this story, he got up to pour himself another glass of tequila.

He called his father. They fought. As always, Rocky denied any wrongdoing. Johnson got so angry that he finally handed the phone to his mother. Soon afterward, he managed to get the autobiography pulled from stores.

That was the last time he and his father spoke.

When Johnson got the news of Rocky’s death, he was in Georgia. It was the first day of filming a new movie, “Red Notice.” He had just pulled onto the set and was feeling that first-day excitement — activity everywhere, the crew loading in — when his phone rang. Johnson almost never receives calls (he prefers to communicate via voice memos), so he picked up. The conversation was short. His father had died in Florida.

When Johnson hung up, he sat there in his truck, processing the news, for what felt like a very long time. He didn’t know what to do. Go home to his family? Fly to his mother? But then, in his head, he heard his father’s voice — one of his mantras, a phrase he said countless times, no matter what, after an injury or an argument or even after news of a death. “Show must go on.” So Dwayne Johnson got out of his truck and went to work.

At Rocky Johnson’s funeral, all the wrestlers showed up. Hulk Hogan, the Wild Samoans, the Bushwhackers, Triple H. They were full of great stories, kind words. “Wildly enough, my old man was just this amazing friend,” Johnson told me. “Complicated husband. Complicated dad. But an awesome friend to everyone else.”

“Was he a better friend to you than he was a dad?” I asked.

Johnson thought. “No,” he said. “He wasn’t my friend either. No, sadly. No one’s ever asked me that. But no. I wish. I wish. I think that my mom was my friend.”

And yet Johnson stressed, over and over, during our long conversation, that there were many good things about his father. He can see them more clearly now that he’s gone.

“I think my dad’s capacity to love was very limited,” Johnson said. “He was kicked out when he was 13. Imagine that pain. And that’s the man who raised me. That was my dad.”

Rocky Johnson taught his son how to work hard, how to survive, how to wrestle. He also taught him, by counterexample, the importance of humility, gentleness, introspection, gratitude.

Maybe the way Rocky Johnson is most present, in his son’s life, is in his words — the little mottos and credos and sayings that still circulate, constantly, through his brain. “Don’t eat to please the tongue — eat to nourish the body,” Rocky would say. (Dwayne learned that one when he was 5.) “They can’t feel your pain, they can only see it.” (This was Rocky’s lesson about “selling” in the wrestling ring — making sure everyone understands how much you’re suffering.)

There is a moment in “The Smashing Machine” when Dwayne Johnson, as Mark Kerr, is driving, talking on his cellphone to a nurse, trying to sweet-talk his way into drugs. Although Johnson’s body is huge — he practically fills the S.U.V. — his voice is pleasant and light. He needs liquid opiates, he tells the nurse, because the pill is “a little hard on my tummy.” The conversation wraps up in a flurry of small talk — “I’m feelin’ really good, I appreciate it” — at the end of which Johnson says, cheerfully, “A day without pain is like a day without sunshine.”

Benny Safdie was sitting in the car when they filmed that scene and found himself amazed by the sunshine line: It wasn’t in the script. “It was just so perfect,” Safdie told me. “Because you don’t necessarily know what it means. But it’s so meaningful.”

A day without pain is like a day without sunshine. Does it mean that you’re always in pain? Safdie wondered. But then sunshine is a good thing. So are you saying you want to be in pain?

“It’s a really loaded, complicated phrase,” he said. “And he says it with a smile.”

As soon as the cameras stopped, Safdie asked Johnson where the line came from.

Johnson, switching back to his real voice, told him that it came from his dad.