It’s always a pleasure to see that funny, smart performer Adèle Exarchopoulos in Cannes – after all, she made Cannes history by being jointly awarded the Palme d’Or for the 2013 film Blue Is the Warmest Colour, sharing the big prize itself with the director Abdellatif Kechiche and her co-star Léa Seydoux. Exarchopoulos has her moments in this film from Jeanne Herry, in which she plays an actor struggling with a drinking problem. The scenes in which we see her up on stage, boisterously performing in a touring theatre for schoolkids, are genuinely great. But really this is a very glib and unsatisfying drama, whose essential naivety becomes apparent when the lead character is forced to confront the crisis in her life.

Exarchopoulos plays a young actor called Garance; she adores Arletty’s character of the same name in Marcel Carné’s movie classic Les Enfants du Paradis. At the moment, she has an assistant stage manager position in a prestigious Paris repertory company, believing herself to be on the verge of getting some serious speaking parts when the next season’s casting is announced. But she is instead relegated to the touring schools company, where her undoubted talents are compromised by partying extremely hard every night and waking up with a terrible hangover every morning.

Garance is one of those people who show up chaotically late to meetings with a drama-queen swirl of excuses about late buses and trains. With an awful inevitability, she is fired from the theatre troupe, a sacking which is made worse by being executed collectively with a stern injunction to get help, like an intervention. She forms a new relationship with a set designer, Pauline (Sara Giraudeau) but this is also placed under pressure by her drinking and she begins to suffer anxiety attacks and depression. To make things worse, her pregnant sister, who is there to be the unimpressed voice of common sense, gets cancer – a contrived health crisis that exists to facilitate Garance’s own path to maturity.

It is when Garance is forced to confront her life choices by a doctor that the film looks very flimsy. This doctor professes herself astonished by how good Garance looks for someone supposedly necking litres of white wine daily. Yes, it is astonishing; she looks like a well-groomed movie star who isn’t drinking anything like that amount. When she finally admits she needs to quit because her liver is packing up, there are some tearful scenes in which she says how “scared” she is but then she just quits, without going to AA. And it doesn’t even look that hard. She is surely therefore what AA veterans call a “dry drunk” or a “white knuckle drunk”, someone who thinks that they can just go it alone. Surely this film isn’t suggesting that you can do it the way that Garance is fancifully shown? It’s a very superficial portrait.