“Ready to do this, buddy? Let’s kick some ass.” Dwayne “The Rock” Johnson has said this line about five times in a row now, as he stands atop a mass of rubble in what will eventually portray a decimated Chicago. In reality, we’re in Atlanta, Georgia, on an unforgivingly hot June day, but the sweat on Johnson’s face is not due to the intense heat, as much as it’​s a saving-the-world kind of perspiration. Each time he delivers the line, he looks back at an empty green screen that will later be filled in with a massive, genetically-mutated albino gorilla. The journalists watching the scene on a monitor inside a nearby tent are all giggling as Johnson does take after take of this line, seemingly talking to himself, but the action star never breaks character—each delivery is stern and serious. He’s 100-percent in the moment.

Dwayne Johnson is shooting a scene for his latest film Rampage, which marks the third collaboration between him and director Brad Peyton, after Journey 2: The Mysterious Island (2012) and San Andreas (2015). Their latest movie once again relies on the charisma and physical strength that the wrestler-turned-actor is best known for. Johnson plays primatologist Davis Okoye, who must save the world and a gorilla named George, after a genetic experiment turns his primate pal into a monster, along with a ferocious wolf and crocodile. Sure, Johnson and Peyton are familiar working within this genre, but they’re also stepping into new, tricky territory by adapting a video game—something few filmmakers have had success with in the past.

Rampage does have a nostalgic ’80s fanbase, but since it was a simple 2D arcade game, there’s not much of a built-in story to work with. In this case, that actually turned out to be a good thing, as it gave Peyton, and his team of writers (Ryan Engle, Carlton Cuse, Ryan J. Condal, and Adam Sztykiel) a lot of narrative freedom. Fans can’t get mad at the story because there wasn’t really one to begin with.

“I’d be scared shitless to do like, Modern Warfare or any game like Assassin’s Creed where you’re like, ‘This game is so deep in its own mythology and those characters are so defined,’” says Peyton. “For [Rampage], I was like, ‘Okay, there’s not a lot of mythology that everyone’s aware of. When I initially got [the project], it wasn’t a type of movie that I would wanna do. It wasn’t very grounded. But then we developed it into a direction where there was more emotion, more grounding, but still maintaining all the fun of it, and it was something both Dwayne and I thought we could really make work, with both his skill set and my skill set.”

Rampage, which comes out April 13, also sets itself apart from other monster apocalypse movies by having the gorilla be a friend, not foe. “I was thinking, ‘We have these cool elements, great CGI, a great director who can deliver on a big massive scale, but what’s the anchor, what is the heart?’ And the heart is in this relationship,” Johnson says about his character’s connection to George the gorilla. “It all kind of falls down to just me and this silverback gorilla. We have not only this awesome relationship, but we do sign language. He tells me, ‘I love you,’ I tell him, ‘I love you back.’ He shows off in front of pretty ladies, I tell him don’t do that. We do some funny stuff.”

Of course, it’s not all fun and games and sweet gestures. After George gets injected with a gene-mutating virus, he grows bigger and bigger and his nature becomes more savage. By the film’s climactic scene, Rampage promises an uncontrollably large wolf and crocodile trying to demolish Chicago alongside a raging George. This is when Johnson’s character of Davis teams up with a scientist, Dr. Kate Caldwell, played by Moonlight star Naomie Harris.

“Davis is very reluctant to partner with anybody, because he’s not a people person at all,” Harris says. “He thinks Kate’s more of a hindrance to be honest. His sole motivation is really because of his friend George, who has obviously been infected by this virus. So, he doesn’t really want her on board, and she has to really earn his trust and find a way to get him to want her to go on the journey.”

Rampage has a completely different vibe from the Oscar-winning Moonlight, but that’s exactly why Harris was drawn to the project. The actress was starting to feel herself typecast in the “haggard mother” role, so she wanted to change things up, and Rampage gave her a character she could really sink her teeth into. “I read the script, and I didn’t expect it to be my kind of movie at all, but it moved me, and I was excited by the character,” she says. “I loved the idea of playing Kate. She was intelligent and capable and fun, all the kind of things I look for in a character.”

The star-studded cast also boasts Malin Akerman, who plays the villain, The Walking Dead’s Jeffrey Dean Morgan, who plays the government agent, and Joe Manganiello and Jake Lacy, among others. But the secret star might be the six-foot-nine Jason Liles, who portrays George through motion capture. He not only studied real gorillas like the famed Coco for the role, but also worked under Terry Notary, the go-to motion capture guy who was in the latest Planet of the Apes franchise and portrayed King Kong in Kong: Skull Island. A lot of Liles’ scenes are filmed in solitary, but he made a point to be on set with Johnson often, so that their on-screen interactions feel genuine.

“I get on set for Dwayne’s coverage and help him go through that by having someone there to actually bounce off of,” he explains. “You have to get to a very, grounded centered place where there’s no such thing as a mistake. To get to that place as a gorilla, you’re so free. It’s like trying to get a dog’s attention. If you can’t get their attention, they take off. I can do that as a gorilla. I can have squirrel moments and they’re like, ‘That was great when you ignored Dwayne!’”

I READ THE SCRIPT, AND I DIDN’T EXPECT IT TO BE MY KIND OF MOVIE AT ALL, BUT IT MOVED ME, AND I WAS EXCITED BY THE CHARACTER.

Harris admits she initially didn’t understand the need for a human actor to fulfill the role of George—that is until she saw Liles at work. “I was thinking, ‘Was that really necessary? Can’t we just have a [stand-in] head?’” she says, laughing. “And now I understand why it’s important, because a head can’t bring all those emotions, you know? It’s vital, actually. Liles’ performance is really moving because George is going through a lot of movements in this movie.”

“As a filmmaker, I always try to lean into the emotion,” Peyton adds. “When I’m 85 and retired, that’s the thing I’ll hopefully be remembered for. I really, really try to push the emotion of it. And in defining the relationship between George and Davis, that was, to me, the anchor of everything in the movie, and therefore gives you heart and purpose and drive and makes you relate to everyone so it’s not just big destruction for destruction’s sake, which is always what I’m trying not to do.”

Still, moviegoers can expect the destruction scenes to be bigger than ever. Rampage is certainly not Johnson’s first rodeo, but even he calls it the most physically demanding role he’s ever done. Sitting in a room surrounded by storyboards and character sketches, wearing a torn and bloodied shirt straight from set, Johnson pulls out his iPhone for the journalists gathered in the room. He pulls up a photo of him and Harris passed out after a particularly grueling day.

“I knew it was going to be physically demanding, because you read the script and you know that things start to happen at a catastrophic level, things are going down all around you, and you’re flying a helicopter, plus I was familiar with Brad… But it wasn’t until I got to the set that I started to realize it is constant,” Johnson explains. “Unlike San Andreas where a little tremor would happen and we’d have a little bit of time [to react], this is just a constant onslaught. So I think we’re going to make a movie that really, truly feels like a ride with amazing twists and turns, and ups and downs, and your heart will beat really fast and then we’ll slow it down just a little bit. Add a little bit of humor at certain places, which you need, and then you’re on it again.”

Johnson snaps his fingers. “This is 12 hours every day, and finally Naomie and I are like this,” he says, pointing to the photo. “And she’s like, ‘Fuck, man, this is tough.’”

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