In the opening scene of Incendies, a notary presents adult twins Jeanne and Simon with the will of their mother. The siblings are given the task of presenting separate envelopes to their father, who they believe passed away in the war in the Middle East, and to a brother they did not know existed. The journey that follows is engrossing and full of tension, as the twins piece together the story of the woman who brought them into the world, discovering a tumultuous and violent life shrouded in mystery.

Directed by Denis Villeneuve from an acclaimed stage play, Incendies was deservedly nominated for Best Foreign Language Film at this year’s Academy Awards but lost out to In A Better World. As the film deftly cuts between flashbacks and the twins’ present-day discoveries, we follow them to the core of the mysteries surrounding their anguished mother as they carry out her last wishes. The result is a confronting film about the strangeness of enduring love, the horror of deeds done in the name of war and the ability to forgive. Of all the impressive performances on display, Azabal gives the most formidable one as the twins’ mother in the film’s numerous flashbacks, as does Abdelghafour Elaaziz as Abou Tarek, a man whose life is tragically interconnected with all concerned.

With a heavy plot that twists and turns its way to a final, devastating reveal in the closing ten minutes, Incendies is the definition of a powerful film.

If you’ve seen other pop musician biopics (Ray, Walk the Line), does this mean you know what to expect from this one? Yes and no. The standard story arc is there, albeit minus the bit where the star’s career is derailed by drugs, but nothing in Gainsbourg feels routine: it’s nimble on its feet, occasionally surreal, and somehow gets away with everything it attempts.

When Gainsbourg (Elmosnino) is trying to ingratiate himself with a younger generation, he writes the shamelessly boppy song “Baby Love” for teen idol France Gall (Sara Forestier). Gall begins singing with typical sulky, adolescent listlessness; yet when she gets to the refrain, damned if the lyrics don’t have an emotional charge, and damned if the singer isn’t suddenly electrified by them herself. (After watching this, read up on the true story of Gainsbourg and Gall: it’ll make your hair curl). Or when Gainsbourg confronts a crowd of patriots infuriated by his reggae parody of “La Marseillaise”, he waxes defiant: ‘Yes, I’m a rebel. And the Marseillaise is a rebel’s song!’ And damned if he doesn’t win the crowd – and us – over by singing it as though he plans to enlist in the French army afterwards.

It’s a mystery to me why critics were ambivalent about this film. Yes, it’s hard to know what to make of it: that’s part of its charm, and its strength. I walked in not knowing Gainsbourg from a bar of soap, and walked out wanting to buy the soundtrack.