This social-realist portrait of the people at the sharp end of France’s employment crisis – the contract cleaners who toil every night for minimum wage, with minimal workers’ rights – is a depressingly timely work. Directed by Emmanuel Carrère, the themes are familiar – there’s a kinship with the work of the Dardenne brothers and Ken Loach – but this adaptation of a factual book by journalist Florence Aubenas weaves in another angle: the central character, played by Juliette Binoche, is not who she says she is.

Marianne is a successful writer who is working undercover as a cleaner in order to gather material for her next book, an exposé of the experiences of invisible contractors and their subsistence on the breadline economy. The film raises a thorny ethical question: is lying and misleading justifiable when the aims are laudable? Is a friendship built on deception even a friendship at all? Binoche is the star and will undoubtedly be the main draw, but it’s an incendiary, scene-dominating turn from newcomer Hélène Lambert that gives the picture its jagged, furious energy.

• In cinemas and on Curzon Home Cinema