Residential schools for Indigenous children have been a stain on the histories of both the United States and Canada, and although steps have been taken in making amends with the past, the new documentary Sugarcane reveals just how much of the process still remains incomplete.

These schools operated throughout the 19th and 20th centuries, with Canada’s last residential school only closing in 1997, and they have been referred to as sites of attempted cultural genocide against Indigenous people. For many children, attendance at these schools was compulsory, forcing them to travel far away from their homes, where they were systematically separated from their language and culture and suffered various forms of abuse. Attendance at these schools has been linked to serious mental health consequences, including elevated rates of depression, substance use and suicide.

New light was recently shed on the level of atrocities that occurred at residential schools when in 2021 it was revealed that potential unmarked graves had been discovered on the site where the former Kamloops Indian residential school once stood. It was this news that spearheaded the creation of the documentary Sugarcane, which investigates the residential school St Joseph’s Mission.

The revelations of Sugarcane are many, but perhaps the most shocking one is the evidence that the film-makers bring forth that infanticide was practiced at this school, where the bodies of children of women abused by Catholic priests were incinerated on school grounds. As it turns out, this horrific discovery has serious implications for co-director Julian Brave NoiseCat, whose father, Archie, may have been the only survivor of these events. Julian makes the courageous decision to place himself into the movie, and we see father and son slowly work through years of estrangement and decades of history to learn the facts about how Archie came into this world.

NoiseCat’s is possibly the most compelling of the four entwined narratives that the movie follows, which include Chief Rick Gilbert, who travels to the Vatican seeking redress for the church’s actions, investigator Charlene Belleau, who painstakingly pieces together exactly what happened at the school, and Chief Willie Sellars, who has organized and led the inquiry into the school’s history.

Although the residential schools have had an immense impact on NoiseCat’s family, he shared with me in a video interview that for much of his life he knew virtually nothing about his grandmother’s experiences there as a young girl. During summers visiting with her, she would offer the strange story of how she and her fellow female students would say to one another “the black bear is coming” whenever they saw one of the school’s priests or nuns. “All I got from my grandmother was this very cryptic accounting of her experience at the residential school,” NoiseCat told me, “where she said that the people who were supposed to be looking out for us were predators.”

NoiseCat’s story about his grandmother indicates the larger silence surrounding these schools, even within the Indigenous community, and this is one of the reasons why this documentary is so important. According to NoiseCat, Sugarcane contradicts the popular view among many in the media that residential schools are well-known and thoroughly discussed within the Indigenous communities. “Every time I heard this,” he told me, “I thought, ‘This doesn’t ring true to my experience.’”

Indeed, when NoiseCat and his co-director, Emily Kassie, attempt to discuss the schools within the community, they are largely met with silence. As the film explores, part of the trauma faced by Indigenous people is that the things they suffered at the schools left them speechless, without a language to discuss the events, or people with whom they could share their experiences. One of the keys to processing and overcoming this past is to learn to talk about it, and for those who suffered to tell the story in their own terms. Both in terms of constructing this narrative, and in encouraging others to do so, Sugarcane is a powerful intervention for the health of the community.

One of the strengths of Sugarcane is how NoiseCat and and Kassie let this reality make its presence felt throughout their documentary. The movie plunges viewers right into the heart of the story, preferring the texture of the lived experience of the Indigenous people over a more straightforward accounting of exactly what happened. “Jules and I talked a lot about what the silences meant, and also reflecting the pacing of this world,” Kassie told me. “This is really what the world feels like, and it was very important to us that it felt representative of what we were seeing and feeling.”

Because of these choices, Sugarcane is a movie that moves at a very deliberate pace. This may challenge some viewers accustomed to punchier rhythms, although this choice gives space to the silences that continue to permeate the community, and it makes the few words that do eventually escape feel hard-earned and substantial. “We didn’t want to tell a story from 10ft away,” Kassie said. “We wanted to tell it from people living it.” This makes Sugarcane extremely effective at reflecting the larger challenges still faced by the Indigenous community as it begins the long, difficult work of confronting its trauma by piecing together the story and speaking about what happened at residential schools.

As the film also makes clear, this is very much an ongoing story. When Gilbert heads to the Vatican to have an audience with a bishop, he does receive an apology but responds that this is not enough: noting that the Bible says that apologies are only the first step in righting a wrong, he tells the bishop: “There have been apologies, but nothing has happened.”

This nothing is a significant part of the systematic failure that traumatized the attendees of the residential schools. Sugarcane notes how attempts were made at the time to report that children were being abused at the schools, but these reports fell on deaf ears. The attempted infanticide of NoiseCat’s father was reported to the police but nothing ever happened. “This was reported to the police, along with records of other victims,” Kassie said, “like finding a body of a baby in a shoe box, and other accounts of babies being taken and forced into adoptions. Nothing was done to follow up on these crimes.” In fact, as Sugarcane reports, the only person to face any criminal liability was the baby’s mother, who was sentenced to a year in jail for neglect of her child.

It is too late for many of the Catholic priests who abused children in the residential school system to be held accountable, but simply sharing the truth of what happened can still have a powerful healing effect. NoiseCat has discussed how screenings of the film often end with audience members experiencing catharsis, and the film documents how the process of being involved with this project has helped many process and overcome their trauma.

“This film is also about the resilience and the love of the community and the families that you see here,” said NoiseCat. “They have endured in spite of how these schools were designed to tear families apart.”

• Sugarcane is out in US cinemas now and in the UK on 20 September