Laurent Bouzereau’s documentary about the life and death of the Hollywood legend is charming but frustratingly incomplete.

Decades after her sudden, mysterious death by drowning in 1981, Natalie Wood‘s shadow still looms large in the show business consciousness. So much so, argues her daughter Natasha Gregson Wagner in the opening minutes of Natalie Wood: What Remains Behind, “it’s overshadowed her life’s work and who she was as a person.” That’s what Gregson Wagner and director Laurent Bouzereau hope to explore in HBO’s latest doc, a straightforward take on the woman who blazed a trail through the silver screen her entire life, only to see it tragically cut short. In focusing on the positive, however, the doc pulls its punches at the critical moments it knows its audience wants to see.

There was a lot to celebrate about Wood’s life, even before we needed to do so post mortem. Through archival footage, film clips, and interviews with family and famous friends (Robert Redford, Mia Farrow, Elliott Gould), Bouzereau charts Wood’s origins as a child star in films like Miracle at 34th Street, through her years as a hard-working young adult star in hits like Splendor in the Grass and West Side Story, and even her pioneering pivot to a sex symbol in her 40s. Generations of film watchers saw her grow up, and in so doing, felt like they grew up with her; as a portrait of Wood’s indefatigable spirit and resilience through an often-treacherous Hollywood studio system, Bouzereau’s doc sings.

But then we get to the family stuff, and things feel a bit more murky. There’s nothing wrong with the use of documentary to probe a family’s memory: many great docs, Dick Johnson is Dead to Circus of Books just two examples from this year, come from the perspective of children turning the lens on their parents to see where they came from. Gregson Wagner, a producer of the film and the author of a memoir that’s coming out at the same time as the doc, is fiercely protective of her mother’s legacy, and so one gets the distinct feeling that the doc is a celebration rather than an interrogation.

That’s all well and good — there’s plenty of Wood’s life that deserves celebration, from her remarkable screen presence to her behind-the-scenes battle with Jack Warner to choose what films she got to work on. According to her children (and both of her husbands, actor Robert Wagner and producer Richard Gregson), she was also a radiant, loving wife and mother.

Most of the film’s 100-minute runtime is dedicated to these sunny aspects of Wood’s life, to hammer home the tremendous loss that is to come. Then, in the tail end of the doc, Gregson Wagner and Bouzereau try to tackle the thorny mystery of Wood’s death, following a fateful night in 1981 off the coast of Catalina Island, where Wagner, Wood, and Wood’s Brainstorm co-star Christopher Walken spent the night on the Wagner family yacht, Splendour. For reasons unknown to this day, Wood was later found in the water a mile from the boat, drowned.

It’s the kind of salacious, shocking story that breeds all manner of conjecture, and has become one of those strange tales of Hollywood legend (Quentin Tarantino even alluded to it in a sideways manner with Brad Pitt’s character in Once Upon a Time in… Hollywood). But as the doc finally throws up its hands and addresses the night in question, What Remains Behind becomes frustratingly transparent in its goal to quash rumors of Robert Wagner’s involvement, however incidental, in his wife’s death.

One gets the distinct feeling that the doc is a celebration rather than an interrogation.

This takes the form of a heart-to-heart sit-down interview with Wagner and Gregson Wagner (who calls him “Daddy Wagner” with great affection), who has him talk through the evening in question. And he does so with great detail, recounting arguments with Walken about Wood’s career direction, a broken bottle, cleaning up that bottle, and eventually discovering Wood had vanished. Gregson Wagner expresses dismay to Daddy Wagner that “anyone would ever think that you would be involved in what happened to her.”

More space in the doc is spent throwing shade at Wood’s sister Lana, another actress from the ’70s who’s long been the primary megaphone for the “Robert Wagner killed Natalie Wood” story. She’s painted as a fame-chaser, someone barely tolerated in her own family. “I don’t even think she believes what she’s saying,” younger daughter Courtney says of her.

This is not to say that any of those rumors have a basis in fact, or that the sentiment behind it isn’t virtuous or true. No one, save Wagner and Walken, the latter of whom refuses to comment to this day, knows what happened on the boat that fateful night. But the begrudging, defensive framing of the discussion itself — a “can’t we just put this behind us?” roll of the eyes — just makes the film feel like it was always designed to clear Wagner’s name first and discuss Wood’s life second. Not every documentary has to be hard-hitting journalism, but it’s disappointing to see such a transparent face-saving agenda on display.

But I get Gregson Wagner’s impulse to use this one-two punch of memoir and documentary to rescue her beloved mother’s legacy. For all Wood’s accomplishments and virtues, it’s a tragedy to see it overshadowed by lascivious true-crime shenanigans. Take away the whodunit angle of Wood’s death, and you have a captivating woman who was at once immensely powerful and intriguingly vulnerable to the pressures of fame and mental illness. Friends discuss her suicide attempts, her stay in a mental hospital, her predatory relationship with the much-older Rebel Without a Cause director Nicholas Ray — all indicators of a woman who’d been through the horrors of life on both sides of the lens.

“How do you separate reality from illusion,” Wood wrote in an unpublished essay for Ladies’ Home Journal called “Public Property, Private Person”, “when you have been trapped in make-believe all your life?” Absent the pall of her passing, this struggle for psychological truth is the true fascination with Wood’s life, one that Bouzereau probes with admirable focus. It’s when the doc has to stop (and stoop) to chase the true-crime mystery that it rings false.

Natalie Wood: What Remains Behind is currently playing on HBO.

Natalie Wood: What Remains Behind Trailer: