Headstrong, vociferous and fiercely intelligent, Maureen Kearney is a classic Isabelle Huppert protagonist. So it’s no surprise that the Parisian screen icon is in fine form in this true-life story of an Irish trade unionist’s fight against corruption, even when the film’s script hits achingly familiar beats.

Adapted from a 2019 book of the same name, La Syndicaliste treads a fine line between political thriller and biopic. We meet Huppert’s Kearney on the eve of the 2012 French election, as Francois Hollande is about to clinch the presidency. With change afoot, not least in the nuclear sector whose workers she represents, Kearney gets word of a secret agreement to sell the state-owned Areva to Chinese investors. Not only does her whistle-blowing lead to a traumatising attack, she is later suspected of fabricating her ordeal, in a series of events that lays bare the cronyism and institutional misogyny at the heart of French government.

Like so many biographical features of recent years – Molly’s Game (Aaron Sorkin, 2018) and The Good Nurse (Tobias Lindholm, 2022) come to mind -, the sheer intrigue of the true story depicted in La Syndicaliste just about overcomes a lacklustre script. It’s got everything we like in a political thriller: shady deals, class struggle, incompetent, perhaps corrupt, police. So without such strong source material already there on a plate for him, one wonders if director Jean-Paul Salomé would manage to hold our attention for the film’s two-hour duration. The one thing more fascinating than this story of startling injustice is how Salomé has managed to reduce it down to something so disappointingly procedural.

It helps that most people haven’t heard of Maureen Kearney. Her story is sparsely documented in English-speaking media – prior to this film’s release, a Google search of her name here in the UK would bring up little more than a barely populated Wikipedia page and a single RTÉ Radio documentary. Though her case is better known in France, where she has lived and worked most of her life, as the plot unfolds we become increasingly disbelieving at both its outrageous events and their lack of coverage overseas.

While the film should be commended for its fleshed-out female characters – indeed, it is only when the women of the story are given the space to speak for and among themselves that the central conspiracy unravels – it makes a fatal error in presenting their male counterparts as Machiavellian caricatures. Luc Oursel (Yvan Attal), the new head of Areva and architect of the China deal, is too comically evil to be believable. His comments towards Kearney and her female peers and his courting of a gaggle of masculine sycophants exist solely to set him up as the “big bad” in a story that is far more complicated than that. Where he could have explored the intersection of patriarchal society, globalisation and the declining power of western industry, Salomé is more comfortable simply saying “men, right?!” Presenting the film’s characters and the structure within which they operate in such simple terms does Kearney and countless women like her a severe injustice.

On the other hand, Huppert is magnificent, and it’s a great relief that we spend almost every frame in her presence. Kearney doesn’t always behave how we’d like her to; she isn’t, as she puts it, a ‘good victim’, and Huppert captures her idiosyncratic behaviour with characteristic ease. The countless indignities that Kearney faces, from the initial attacks to repeated intimate medical examinations to disprove her account, require a truly physical performance. Her pain, frustration and bafflement at the sheer absurdity of her ordeal are written all over her face and body.

Salomé deploys a frenetic visual style that permeates even the most mundane, dialogue-driven scenes with its pacey movement and choppy editing. It isn’t always clear what the intended purpose of this is: does it reflect the whiplash effect of Kearney’s being thrown around the political and corporate machine? Or is that being too kind, with the idea really being to pile on the pace to liven up a fairly uninspiring script? Once again, the film has all the hallmarks of a thriller, it just doesn’t always thrill.

The remarkable life of Maureen Kearney and the equally remarkable performer entrusted with portraying her are the two key components that make La Syndicaliste worth the price of admission. While it fails to push the envelope in terms of style, Salomé’s film does serve an important function in unveiling a criminally underreported story. And what a story it is.

La Syndicaliste is in cinemas on Friday, June 30th. On BFI Player on Monday, August 21st.