The ninth of November 2016 was a transformative day for many Americans. The day after the election that sent Donald Trump to the White House spurred new personal resolve from coast to coast; for a new generation of political challengers, this was the road-to-Damascus moment that compelled them to take action and launch a campaign, and for Rachel Lears, this was her call to capture it all. She could smell change in the air, for worse but also for better, and wanted to create a living record of the latter.

“I started this process working with the organizations Brand New Congress and Justice Democrats to get in contact with the people that they were considering supporting,” Lears tells the Guardian. “They were recruiting people, and some of our conversations started before the candidates had even launched their campaign. Each of them saw the value in telling their story even before they knew what the story was going to be.”

Lears selected four subjects for the feature that would ultimately blossom into her film Knock Down the House, premiering on Netflix this week. She trained her lens on Cori Bush, a woman of color who thought Missouri’s seats in the House of Representatives should reflect its diverse populace. She followed Nevada’s Amy Vilela on her tireless crusade to overhaul healthcare after insurance complications resulted in the death of her daughter. She went to West Virginia’s coalmining belt, where Paula Jean Swearengin ran on a platform of cleansing the pollution that had choked out their community. And she took a special interest in a bartender from the Bronx named Alexandria Ocasio-Cortez, a far-leftist with new ideas and an electrifying presence with which to sell them.

“When you’re making a vérité film, you never know what the story’s going to be,” Lears says. “You try to imagine which way it might go, and you game out scenarios, but you can’t ever really know.”

She could not have possibly anticipated AOC fever, the groundswell of support that landed the then 28-year-old on magazine covers and talkshows. As Ocasio-Cortez’s star continued to rise, Lears found herself at the center of something big and vital and thrilling: a real-life underdog story. Getting in on the ground floor afforded the director a uniquely advantageous position for chronicling the seedlings of a revolution.

“There was a process of communication getting a little less direct,” Lears recalls. “In every campaign, there came a moment when I was talking to comms directors and campaign managers to coordinate stuff instead of the candidates themselves. We negotiated access with everyone along the way. There were a lot of conversations, and of course there was stuff they didn’t want filmed. But there wasn’t a lot of hands-in-the-face. We worked everything out through dialogue.”

Lears didn’t want any one candidate to emerge as the star of the film, preferring to keep the focus squarely on the collective effort that these four women jointly represented. She held herself to a journalistic standard that would promote policy and ideology over a cult of personality.

“The purpose of the documentary is not to create a platform for the politicians,” Lears explains. “The purpose is to tell a story about a historic moment, and what it was like for the people inside it, and how the politically impossible becomes possible. We maintained strict editorial independence, we got all our funding through non-profit sources, we didn’t share any footage with the candidates for their own promotional purposes. No conflicts of interest. There was a big red line in the sand, to mix a metaphor.”

Cori Bush. Photograph: Netflix

The style of Lears’s on-the-fly handheld camerawork reinforces her assumed position as embedded reporter, rather than the well-trained film-maker she is. The scene in which Ocasio-Cortez receives the news that she has beaten the odds to win her district is the kind of footage any documentarian would kill for, and yet Lears must be strategic about how she shoots it. The newly minted congresswoman first realizes she has won upon hearing a ruckus while outside the bar where her victory party will be held, and so the shot frantically follows her as she runs inside before cutting to a second camera catching her entry from the front. We share in the overwhelming energy of the room, getting a vicarious taste of the triumph.

Lears knows all too well that nonfiction film-making doesn’t allow for the safety net of second takes: “There are always bits you kick yourself for missing, or parts you can’t include because they’re too sensitive or would raise legal issues. And there’s always great stuff that has to end up on the cutting room floor. That’s the science of documentary film-making; for me, it’s like a collage, making something by shaping the material you’ve been given.”

She sculpted the months leading up to the 2018 primary into a declaration of purpose for a revived Democratic party, a new politics committing to a removal of big money and a restoration of power to the people. It’s Lears’s version of service journalism, as she does her part to introduce the next wave of lawmakers and dispel misconceptions. In other words, she hasn’t lost any of her personal momentum she gained that fateful day in November, continuing the battle to equalize and civilize.

“We’ve had incredible responses from Republicans and even Trump voters who see it at festivals, and come up to us sometimes even in tears and tell us how much they were moved, and how it changed their conceptions. One woman said to us: ‘All I knew about AOC was what I’d heard on Fox News and now I see that she’s really different than that.’” She gives the matter another second of thought. “I am also sure that there are people who see the movie and remain totally unconvinced.”