For more than two decades, Larry Nassar used his position as an osteopathic physician at Michigan State University and longtime doctor for the United States’ women’s gymnastics team to molest at least 250 women and girls under the guise of medical treatment. The manipulation ran so deep that his victims for years believed there was nothing to report. In many of the cases the abuse happened while a parent was in the room, a tragic detail that offers an alarming metaphor of how blind we can be. It was literally happening in front of our eyes.

Not until a former gymnast named Rachael Denhollander became the first woman to publicly accuse Nassar in September 2016 – more than a year before #MeToo and the tipping point of a society’s reckoning with sexual assault – were Nassar’s many victims emboldened to break their silence. Denhollander’s courage encouraged more survivors to come forward, including Olympic champions and household names like Simone Biles, Gabby Douglas, McKayla Maroney, Aly Raisman and Jordyn Wieber, until the trickle became a deluge, generating the momentum necessary to bring a pillar of the community to justice – and not without initially severe public backlash.

This, the biggest sexual abuse scandal in US sports history, is the subject of At the Heart of Gold, Erin Lee Carr’s documentary that airs on HBO after premiering at this year’s Tribeca film festival. On the surface, the blend of archival footage and talking head interviews with current and former female gymnasts doesn’t offer a whole lot that hasn’t previously come to light. Nassar’s grooming techniques had already been recounted in stomach-turning detail during his trial, while the many institutional failures that enabled the abuse were laid out exhaustively in the Ropes & Gray independent report commissioned by the US Olympic Committee in the aftermath. None of the big-name Olympians who spoke out against Nassar in court last year participated in the filming.

And yet the 88-minute film succeeds where mainstream media too often failed as the story unfolded, making full use of its feature-length canvas in pulling together the many complex threads of a story that was always bigger, and more sinister, than a single monster.

“I was and am a big fan of the Olympics, of Americans going forth on the international stage and trying to win medals for their country,” Carr told the Guardian. “I believed in the beauty of that. But in researching and producing this doc, it showed me the institutions that build these young women to put them on that trajectory toward the Olympics are not looking out for their best interests. They’re predatory.”

She added: “Documentary is an incredible format to not just hear or read the words that these women are saying in court but to feel it. One of the most iconic parts of the film is the look on the face of the mother of Kyle Stevens, the only non-medical Nassar survivor to come forward. The expression on her face. She doesn’t say anything but her face says everything.”

There are any number or reasons why contemporaneous news coverage of the Nassar scandal was lacking. Maybe it’s because the story centered on a sport to which people rarely pay attention during non-Olympic years. Maybe it’s because it involved the less familiar terrain of abuse by a doctor, unlike more common cases of sex abuse involving teachers or coaches. Or maybe it’s because abuse of women is normalized in our society and the scandal fits into our framework of how we understand women’s gymnastics: that on some level we expect young women to be victimized, so it’s less surprising when they are.

Outside the courthouse of the Larry Nassar trial. Photograph: HBO

But the most practical reason is a simple one: it’s a more complicated story than what happened in similar cases at Penn State or Baylor, harder to parse or boil down to a digestible tagline.

Carr spares no ancillary player in her retelling, shining a light on the people and institutions that allegedly enabled or were negligent in preventing Nassar’s abuse and explaining how reports dating as far back as 1992 were dismissed, disbelieved or ignored by coaches, administrators, counselors, police and university-employed trainers.

Extensive sections are devoted to: Bela and Martha Karolyi, the former national team coordinators widely credited with transforming the United States from outsider to the head of the sport’s new world order, who are cast as complicit in engendering an environment conducive to Nassar’s abuse; former USA Gymnastics president Steve Penny, who faces witness tampering charges for allegedly ordering the removal of documents from the Karolyi ranch; Kathie Klages, the former Michigan State coach who is facing prison time for allegedly failing to move on reports of Nassar’s behavior as early as 1997.

It’s a raw, difficult piece of work. But Carr believes the audience is ready for it.

“There used to be a deep cultural fatigue when it came to instances of abuse,” she said. “One of the ways we tried to combat that is to rely on the beauty of the sport [in the film]. But secondly we are believing survivors in a way we didn’t used to.

“It took all these women coming forward and going on camera and having their identity tied to being a sex abuse survivor for people to wake up. We cannot have their efforts and their sacrifice be in vain. This film is a testament to their bravery in stepping forward as they did in the courtroom.”