Barbie is living happily in Barbie Land, dancing with her fellow Barbies in her pastel world, when out of nowhere, she blurts, “Do you guys ever think about dying?”

The question comes as a jolt, not just to the other Barbies, but to the audience. It’s the moment we realize that “Barbie” is not just going to be about set design and bringing a toy world to life. This is going to be a caustic comedy that uses the most popular doll in the world as a platform to discuss the difficulties and terrors of being human.

Directed and co-written by Greta Gerwig, “Barbie” is a glowing live-action film that depicts Barbie Land and the real world as parallel realms that can be crossed through a special portal. Gerwig (the Sacramento native behind the Oscar-nominated “Lady Bird”) and her husband and co-screenwriterNoah Baumbach(“White Noise,” “Marriage Story”) give us a complicated set of rules as to how these worlds interact, but they do it in a way that seems effortless.

“Barbie” is an impressive and original work of the imagination. Its story holds up most of the time and for most of the way, with the unifying through line being Barbie’s existential crisis.Margot Robbie也是电影的制作人,Stereotypical Barbie (that is, the original Barbie), who lives a life of endless peace and pleasure. The Barbies rule in this world. They are the doctors, the politicians and the judges, while the Kens — including Beach Ken (Ryan Gosling) — just stand around waiting for the Barbies to look at them.

Then something intrudes on Barbie’s idyllic universe. She has a sudden, out-of-nowhere awareness of death, followed soon after by her discovering that she has developed cellulite. The cellulite bit is, of course, funny, and Barbie’s reaction to it is something any woman can understand — she doesn’t like the way it looks. But this is essentially about her realizing her own mortality, and that makes the story universal. She is finding out what life is about, that this is the deal.

The screenwriters let their imaginations run free here, but always within the parameters they’ve established. So, when they place Barbie in modern-day Los Angeles, they think about what Barbie might expect from the real world, and how people in that world might react to her.

They ask the same questions about Ken. How might Ken, who has always been a second-class citizen, respond to an environment in which men are on all the currency and in which most politicians and business leaders are male. Watching Gosling go from dejected servility to imbecilic self-satisfaction is one of the comic pleasures of “Barbie.”

But “Barbie” loses its sense of humor for a significant stretch. It starts taking itself seriously and funneling its imaginative world through a set of politically correct tropes. Of course, any truthful movie about Barbie, comedy or otherwise, is going to be about the experience of being a woman. But when we start hearing about “the patriarchy” and whenAmerica Ferrera, as a real-world woman, makes a speech about the “cognitive dissonance” of a woman’s life, we encounter the sort of virtue signaling that is making movies boring.

The truth is, though Ferrera (“Ugly Betty,” “Superstore”) makes a good speech, easily 60% of what she says can also apply to men, and men have their own gender-specific problems. The real power of “Barbie” is in its spiritual implications, its ideas about whether a life of struggle is worth it, and whether it’s better to live in ignorance. At its basis, “Barbie” is like a Garden of Eden parable.

Fortunately, the movie rights itself, and the ending is more than lovely; it has a touch of the profound.

Robbie, who always strives for the truth of a character (even when there’s no truth to be found, as in those awfulHarley Quinn movies), doesn’t just play a toy. She commits absolutely to Barbie’s emotional journey — her panic, her disillusionment, her anguish, her burgeoning courage. Robbie finds whatever depth was put into that role and runs with it all the way home.

Reach Mick LaSalle: mlasalle@sfchronicle.com