“People wouldn’t send their daughters to Immaculate Heart because it felt a little dangerous,” someone can be heard saying in “Rebel Hearts,” a surprising statement about a nunnery in Pedro Kos’ compelling history of a Los Angeles convent that changed with the times between 1962-1970 far more than the rest of the Catholic Church had that begs the question, dangerous to who?

You certainly wouldn’t be afraid to step onto the campus of Immaculate Heart, a college adjoined to a Mother House in Los Feliz where art and music were bountiful, with Sister Corita Kent attracting international interest in her innovative serigraph paintings. But even as the Second Vatican Council convened to relax rules around the religion when its conservatism threatened the potential to attract new parishioners, Cardinal James Francis McIntyre wasn’t about to accede to them in his own parish where there was a battle brewing given his insatiable desire to extend his reach with new schools in Los Angeles and his savvy yet utterly impious use of nuns, bound by their faith to serve the Church, as teachers without proper salaries.

As “Rebel Hearts” elegantly lays out, a labor fight was not one you would want to pick with the women who found their way to Immaculate Heart, with many seeking out the Church as a rare place where they could receive a higher education and take a different path in life than marriage and children, and already involved in some of the biggest civil rights battles of the era, whether it was the farm workers’ movement happening upstate or the civil rights movement springing up in the South, the sisters at Immaculate Heart were prepared to take on McIntyre’s iron fist, seeing it as a naked attempt to keep power in the hands of the same white men that had always held it.

The fact that it still comes as a surprise to see these nuns in a progressive light with various interests may be testimony to the enduring power that these men still have over the public imagination, but “Rebel Hearts” impressively chips away at this fixed image and Kos and co-editors Erin Barnett, Yaniv Elani and Ondine Rarey cleverly structure the film in such a way that acknowledges leaders such as Sister Corita and Sister Anita Caspary, who served as Mother General at Immaculate Heart, but emphasizes the collective that made an effort to break away from the Church a force to be reckoned with. Held together with Una Lorenzen’s clean and bold animation and a propulsive score from Ariel Marx, the film draws on first-hand testimony that was obviously compiled over a number of years, ensuring its main participants wouldn’t take their experience to the grave after Cardinal McIntyre worked so hard to silence them.

From the start of “Rebel Hearts,” it’s inspiring to see that there are Immaculate Heart alums to this day still out there on the streets in the name of social justice, but equally poignant is how the film shows that they were always there, believing the Church at first to be their best way to pursue a righteous life in a society that largely prevented it. It may have taken some time to be recognized, but when the power structures that have existed for centuries have relied on people to believe that things will never change, the opportunity to see in “Rebel Hearts” that a resistance has long been lurking under the surface gives plenty of hope.

“Rebel Hearts” will screen once more at the Sundance Film Festival for a 48-hour window beginning January 31st at 7 am MT.