Dwayne Johnson has finally found a co-star who's bigger than "The Rock."

Dwayne Johnson takes on three genetically mutated creatures in the action adventure 'Rampage,' based on the 1980s arcade game.

In the action adventure Rampage (in theaters April 20), the larger-than-life Johnson plays a heroic primatologist whose best friend is a 7-foot-tall, 500-pound rare albino silverback gorilla named George. “I’m pretty sure on paper he’s smarter than me as well,” Johnson quips.

Thanks to an experimental serum gone wrong, George and other creatures grow enormous and go on a path of destruction in Rampage, an adaptation of the 1980s video game that’s also grounded in real gene-editing science.

“Like with anything that powerful, you have to really be careful that you’re utilizing it wisely and not for the wrong reasons,” Johnson says.

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The former pro wrestler and Fast and Furious regular stars as Davis Okoye, a guy who gets along with animals way better than people. “When animals like you, they lick you. When they don’t like you, they eat you. That’s his philosophy, which has gotten him far in life,” says Johnson.

Davis notices George getting more sizable and consequently more uncontrollable, and as he tries to help, it soon becomes clear the gorilla’s not the only beast affected: By the end of the movie, Davis is trying to keep George, a 30-foot wolf named Ralph, and Lizzie, a crocodile the size of a football field, from wrecking Chicago while also attempting to save his friend. (George is played via performance-capture by 6-foot-9 actor Jason Liles, and all three are romping, stomping CGI creatures created by effects house Weta Digital.)

Director Brad Peyton and Johnson last teamed for the hit San Andreas two years ago, and as intense a disaster film as that was, “you have to ratchet up the dial 10 times with Rampage,” Johnson says. “These monsters are relentless, and audiences are going to find that ride very exhilarating. As an actor in the movie, it’s fun and daunting. It’s 12- to 14-hour days of survival, and it’s not quiet survival either.”

Primatologist Davis Okoye (left, Dwayne Johnson) teams with genetic scientist Dr. Kate Caldwell (Naomie Harris) to save his gorilla buddy in 'Rampage.'

Naomie Harris co-stars as genetic scientist Dr. Kate Caldwell, who teams with Davis; Jeffrey Dean Morgan plays a government agent named Harvey Russell tracking the rampaging monsters; and as villainess Claire Wyden, Malin Akerman “not only can carry the screen but can also be captivating and really believable in terms of her malevolent nature,” says Johnson.

Growing up in Hawaii, Johnson plunked a lot of quarters into Rampage arcade machines “when I was a young teenager spending way too much time at pool halls, especially when school was actually in session,” he says, laughing. Johnson also fostered a fascination for things of gargantuan size, from King Kong and Godzilla to Ultraman and Voltron.

“Even when I was a kid, when you watch these movies everyone is looking up at something and terrified,” Johnson says. “As a character, I loved that position where I’m looking up and there’s nothing you can do but try to survive these three gigantic mutated monsters.”

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As part of his Rampage research, Johnson spent time with folks from the Dian Fossey Gorilla Fund as well as experts and animals at the Atlanta Zoo to understand a silverback gorilla’s psychology, energy and behavior. 

“That was really eye-opening for me in terms of how dangerously close we are to having these beautiful animals extinct,” says Johnson, who adopted a baby silverback at the zoo. “There is a much greater level of empathy and care and consideration that we have to have.

“I was an animal lover before, but after this my love has become boundless.”