There is real and genuine fear about young people’s use of pornography; usually, that conversation is about exposure to porn online, not in libraries. But this excellent culture wars documentary tells the story of book-banning in red states such as Florida and Texas, where religious rightwingers are crusading to protect children from “obscene” books. Usually that means titles about LGBTQ+ issues or race, and books about girls getting their period aren’t safe either. In Tennessee, a school board banned Maus, the graphic novel memoir of the Holocaust by Art Spiegelman, for mouse nudity. The utter nonsense of it would be funny if it wasn’t so disturbing.

The most recent purge began in 2021 with a list of 850 books circulated by Texas state representative Matt Krause (over 60% were books with LGBTQ+ themes). Rightwing Florida governor Ron DeSantis piled in, followed by Moms for Liberty, a rightwing parents’ rights group (don’t ask them about big dollar funders). Documentary maker Kim A Snyder and her editors cleverly work in footage of Nazi book burning and clips from classic movies and TV into their film.

Out on the frontline, in school board meetings and public libraries, conservatives vent their outrage. In Granbury, Texas mum of nine Monica Brown believes her pastor should pick the books stocked in the library. Her gay son has other ideas. The heroes of the film are the librarians. Ordinarily, it would be tempting to insert a joke here. But these (mostly) women risk being fired from their jobs, and are routinely targeted with hateful vitriol. “Pornographer!” “Paedophile!” yells one man at a meeting, blood vessels popping. Another guy brings along a firearm: “I know where you live.” Incredibly principled and brave, the librarians talk about their vocation and standing up for the young people for whom libraries are a safe space where they can discover their identity in the pages of books. They really are superwomen.

• The Librarians is out on 26 September in the UK and US.