Shia LaBeouf and Vanessa Kirby in 'Pieces of a Woman' (Benjamin Loeb/Netflix).
CNN  — 

The first half-hour of “Pieces of a Woman” is a brutal viewing experience, portraying a home birth gone wrong in grueling detail. How the audience processes that will likely determine how they feel about the rest of the film, which is otherwise most notable for its powerful central performance by “The Crown’s” Vanessa Kirby.

The premise is loosely inspired by a personal tragedy that befell Hungarian director Kornel Mundruczo and writer Kata Weber, a real-life couple that lost a baby. But their first English-language film takes off in dramatic directions thereafter, including the toll the situation exacts on Kirby’s Martha and her husband Sean (Shia LaBeouf), as well as others within their extended orbit.

LaBeouf, notably, is currently the subject of off-screen controversy, and Netflix has largely excised him from its promotion for the movie.

The film’s emotional thrust stems from Martha’s haunted, numbed response, which has implications for her marriage; her relationship with her imperious mother (Ellen Burstyn), who is determined to intervene, but in ways she sees fit that don’t necessarily help; and the midwife (Molly Parker) who participated in the delivery, leading to a trial that feels like a tired device in order to heighten the drama.

The deeply personal nature of the material shows, and Kirby captures that with the kind of understated performance that conveys the turmoil and pain within her character. In this peculiar awards season, she’s garnered a degree of buzz that frankly outshines the film.

Still, “Pieces of a Woman” is no picnic to watch. The presentation is exceptionally raw, beyond just the torturous end of the pregnancy, including the interactions between Martha and Sean, the latter being particularly ill equipped in how to respond.

The couple’s commitment to a home birth also complicates the story, raising questions about where their responsibility lay in terms of seeking a higher level of care once the situation began to go sideways.

It’s provocative stuff, sure to elicit strong reactions and even conversations that go well beyond the film itself. Yet the latter half feels strained in ways that do as much to undermine the movie as enhance it.

“Pieces of a Woman” is thus most memorable as a breakout showcase for Kirby, who has played several high-profile supporting roles (including the “Mission: Impossible” movies) but seems poised to move into a higher tier of stardom. That includes another starring role in the period romance “The World to Come” in February.

The title, though, is actually unintentionally appropriate, to the extent that the movie, finally, adds up to something less than the sum of its parts.

“Pieces of a Woman” premieres Jan. 7 on Netflix.