When Ryan Gosling first got the screenplay to "Barbie," the title page read "Barbie and Ken" with the "and Ken" crossed out. It was the first sign that this particular script — co-written by the film's director, Greta Gerwig, working with her life partner and frequent collaborator, Noah Baumbach — would be full of untamed wit.

"It just was like nothing I ever could have expected," Gosling says. "Greta so brilliantly constructed it almost like an amusement park where you need no map. It's just been designed so that you naturally ride the rides that she wants you to ride."

In the world of the film, there is "Barbie Land," where the perfectly blond and beautiful Barbie (Margot Robbie) lives a frictionless, uncomplicated life marked by days at the beach and nighttime dance parties with her friends. More Barbies (Issa Rae, Hari Nef, Emma Mackey and Alexandra Shipp, among others) are the president, lawyers, doctors and prize-winning authors. As Helen Mirren's narrator intones, "All problems of feminism and equal rights have been solved."

That is until Robbie's Barbie suddenly begins to have recurring thoughts of death and cellulite. Her boyfriend, Ken (Gosling), already lives a life marked by insecurity and anxiety, only at ease when he has Barbie's attention. When Barbie decides to venture to the Real World in an attempt to solve her newfound problems, Ken tags along. There he learns about the patriarchy — and that he loves it — bringing those ideas back to Barbie Land to rechristen it his "Ken-dom" and refashioning Barbie's dream house into his "mojo dojo casa house."

And still, all he wants is for her to notice him. (It's a sweet kind of rebellion.)

So although the movie is definitely called "Barbie," it is Ken who unexpectedly provides its emotional center, with Gosling's performance arguably among the most rounded, poignant and plain greatest of his career.

As Ken. In the "Barbie" movie.

Gerwig says: "There was something really early when Noah and I were working on it — Ken as an accessory and how forgotten he is — we just felt, psychologically: That's going to be the story. There's (a) story there. How could there not be?"

Gerwig and Baumbach, who co-wrote the screenplays to the Baumbach-directed "Frances Ha" and "Mistress America," did extensive research into the history of Barbie, including such discontinued characters as Barbie's pregnant friend Midge and Earring Magic Ken. (The "Lady Bird" and "Little Women" filmmaker was brought onto the project by Robbie, who as a producer obtained the rights from toy company Mattel through her company LuckyChap Entertainment.)

They took the work of creating the wildly stylized world of the movie quite seriously, and as Ken emerged, it became clear that portraying him would require a unique set of skills. Not just good looks, but also a comedic agility and a dramatic gravity that can be hard to find in a single performer.

"I didn't know Ryan at all," Gerwig says, "but Ryan was the person who was always in my mind going to play this role. I just knew he could be really funny but also would mine the depths of this kind of outrageous conundrum that Ken finds himself in, as a person."

Gosling, who as a child performer appeared on the 1990s revival of "The Mickey Mouse Club," has become one of the most charmingly enigmatic actors in Hollywood, with the leading-man looks of classic stars but an offbeat charisma distinctly his own. A two-time best actor Oscar nominee for "Half Nelson" and "La La Land," Gosling has studiously avoided the superhero and franchise parts that have bogged down so many of his contemporaries, opting instead for unpredictable roles in films such as "The Notebook," "Drive," "The Nice Guys," "Blade Runner 2049" and "First Man." A through line in his work is that, for all of his brooding intensity, there's often a lightness underneath.

"It was the gravitas he's able to bring as an actor that was part of what made everything so heartfelt — but also so funny," Gerwig says.

Gosling and Gerwig sit together in a Los Angeles hotel as part of the pink-hued whirlwind press event around "Barbie," made with a reported production budget of $100 million. Simply getting them into the same room at the same time was no small feat: Gerwig would soon be on her way to a promotional tour of Australia and South Korea, while Gosling would head to his native Canada.

Suddenly a voice enters the room and asks, "Can I crash?" It's Robbie in a dazzling canary-yellow Chanel outfit. Since Gosling won't be making the trip to Australia, the Australian-born Robbie wants to be sure to give him a bag of honey-soy-chicken potato chips, which she declares one of her top three "chippie" flavors. As startlingly as she arrived, she is gone. On her way out the door, she trills, Harley Quinn-style, "Honestly, it tastes exactly like honey-soy chicken. You'll see. Sorry for interrupting."

Gerwig and Gosling are both left beaming. "Classic Robbie right there," says Gosling.

"That is exactly who she is, 100% of the time," Gerwig adds. "She's like a beautiful lady who comes in and gives you food and gifts. I've been working with her on this for four years and there is no bad side. She's just like an angel. I love her so much. I wish I could be like her. I'm always like, 'What would Margot do?'"

"She might be one of the most capable people I've ever met," adds Gosling. "If you were on a plane and the engine went out, you'd want Margot Robbie on your plane."

Robbie's big Barbie energy takes a few moments to dissipate. Settling back in, Gerwig returns to explaining the origins of the stylized "dream ballet" dance number tucked inside the extended musical performance that is the power-ballad "I'm Just Ken," a showstopping highlight sung by Gosling and written by Mark Ronson and Andrew Wyatt, who won Oscars for their work on the "A Star Is Born" hit "Shallow."

The dance number has its basis in the 1950s Gene Kelly musicals "Singin' in the Rain" and "An American in Paris." And while the extended interlude was not in the original script presented to Gosling, Gerwig said she "baby-stepped" everyone involved toward the idea, which to her seemed an obvious if oddball decision.

"I do remember everyone, including Noah, was like, 'What is this dream ballet you want?'" Gerwig says. "And I was like, It's going to be great. I just felt like it was just right there. It was exactly what the moment wanted to be."

There had been rehearsals for Gosling to dance in a Sylvester Stallone-in-the-'80s-style, full-length mink coat that Ken wears once he becomes obsessed with men's rights, so Gosling wasn't thrown by the addition of an even more elaborate dance number just before shooting began.

"It felt so organic, as this whole process has," Gosling says. "We were talking a lot about just being kids and coming from that place in a lot of these scenes. And when I was a kid, I was working and I was dancing at the mall or singing at weddings.

"And I thought, you know, that kid worked really hard and got me here. I owe everything to him, but I thought I had let him retire. Like, he'd worked enough and I could take it from here. But it was time to pull him out of retirement one more time for one last heist."