Is there a finer actress working today than Marion Cotillard? Most probably not. Because in the hands of anyone else, Deux Jours, Une Nuit could be mind-numbingly dull. Thanks to her, it’s captivating.

This is a French film. A really French film. For what, apart from a strike or a ripe brie, could be more French than a social realist drama concerning the rights of the workers? Our heroine Sandra (Marion Cotillard), is a factory worker who has been on extended sick leave with depression and is now ready to return to work. However, her colleagues have maintained productivity levels without her. So why should her company pay one more salary than is needed?

Sandra’s colleagues were therefore issued with a vote: i) choose to allow Sandra to return to work OR ii) choose to receive their annual EUR1,000 bonus. Unsurprisingly, colleagues voted to sack Sandra and receive their bonus. But, on discovering misinformation was spread to influence voting, permission is granted for a re-vote, giving Sandra one critical weekend to try and persuade colleagues to choose her, not their bonus. Desperate, ashamed and exhausted, she visits each in turn, listening helplessly to responses across the moral spectrum, from feeble excuses about needing the money for home improvements, to undicided ambiguity, to emphatic support.

We’re no employment lawyer, but surely none of this is legal? Anyway, let’s not obstruct a good moral dilemma. For what could be a dry, heavy handed tract about money being the root of all evil, in Cotillard’s hands becomes gripping, emotional and very human. The film asks a simple question – what is more important, the individual or the greater good? And as Sandra asks this of each colleage it asks the same question of us. Would we spurn our own gain to help another? Vive Le Socialisme! Vive La Cotillard!

UK release 22 August