A young woman’s flinty, brooding recovery from the devastation of losing a baby is the beating heart of “Pieces of a Woman,” an intimate if somewhat problematic melodrama from the Hungarian filmmaker Kornél Mundruczó (“White God”) and his frequent collaborator, Kata Wéber.

It lives on a riveting, introverted turn by Vanessa Kirby and a bravura early scene — a single-shot “long take” that captures a home childbirth that goes wrong. “Problematic” and “melodrama” fits most everything else.

Kirby is Martha, very pregnant when we meet her, making her goodbyes at an office baby shower, heading home to give birth soon with maternity leave to follow.

Shia LaBeouf is her rough-hewn partner, Sean — a bearded, blustery construction worker building a Boston bridge, somebody we instantly sense is beneath Martha’s class. Her mother (Ellen Burstyn) buying them a minivan reinforces that.

The birth scene that follows is a quiet exercise in rising, single-shot tension. The planned midwife can’t make it. A substitute (Molly Parker) arrives and things progress, in realistic detail, to that instant when it all goes wrong.

Months later, Martha is back at work, brushing off Sean, who insists “We’ve gotta FINISH this,” and pushing back at her pushy, controlling mother.

“Don’t you want someone to answer for this monstrosity?”

They’re arguing for a civil suit. They want the midwife to pay. Martha, still in shock, still silently grieving, seethes at their interference. The viewer is naturally on her side.

But as months pass and the pressures mount, we see Martha withdraw more and more from the event even as she never really comes to grips with it. And even as she doesn’t, the wheels of justice are turning. Sean and her mother and their lawyer are getting their way.

Mundruczó and Kata Wéber, reworking a stage piece they did and based this on, give the film a European flavor, a disconnect that mirrors Martha’s own unmooring. She is pulling away from Sean and her mother, even her sister (Iliza Shlesinger) as this dark winter of her life passes.

But other issues introduced here play like the naked plot contrivances they are, twists and layers to the melodrama that feel like afterthoughts.

And then there is the casting, which makes it hard to lose oneself in her story in some cases.

LaBeouf’s trademark antic aggression paired with his dressed-down/grunged up look and mien feels off. What’s this tall, willowy blonde from money — Jewish to boot — doing with this “rough” and “poor” and “boorish” — words he’s heard from her mother and Martha herself — doing with her?

Everything we learn about him adds to that impression.

Burstyn is an 88 year-old screen legend, and she’s supposed to be this 30ish woman’s mother? That bit of tricky math is ignored to accommodate a Holocaust survivor speech, which Burstyn knocks out of the park, in the shaky voice of very old age.

But come on.

Cinematographer Benjamin Loeb deserves kudos for that single-shot that doesn’t look like a single-shot childbirth scene, a camera in close and backing out, following the stages of labor from room to room with realistic interior lighting.

Montreal, and Oslo and other Norwegian locations substitute for Greater Boston in a mildly disconnecting way.

It’s Kirby who makes this worth watching, and even that performance is nothing anyone would call “warm.” If “The Queen” and a “Mission:Impossible” villain didn’t make her a star, this certainly will.

It’s all the “pieces” around Kirby that let down this “woman.”

MPA Rating: R for language, sexual content, graphic nudity and brief drug use

Cast: Vanessa Kirby, Shia LaBeouf, Ellen Burstyn, Iliza Shlesinger, Benny Safdie and Molly Parker.

Credits: Directed by Kornél Mundruczó, script by Kata Wéber and Ansuman Bhagat . A Netflix release.

Running time: 2:07