In 1985 Jan Jönson staged Waiting for Godot with inmates at Kumla, a maximum-security prison in Sweden. The actor-turned-director initially only had the rights to the first act, until Samuel Beckett arranged a meeting in Paris during which the Irish playwright cleared the rights on the back of a napkin in pencil. What happened next was described by Beckett as “the best thing to happen to my play since I wrote it”.

The Big Hit — or Un Triomphe, to use its original title — modernises, fictionalises, and Frenchifies Jan Jönson’s colourful attempt to help prisoners stage Waiting For Godot. In Emmanuel Courcol’s version, Étienne (Kad Merad, a presence as amiable as the film around him) takes a job teaching drama in a prison. An ageing actor who has never achieved the stardom he craves, he introduces fables and animal sound exercises to a motley crew that includes the illiterate Jordan (Pierre Lottin); Patrick (David Ayala), who only wants to impress his wife, immigrant Moussa (Wabinlé Nabié); gatecrashing hard-man Kamel (Sofian Khammes); and Boiko (Aleksandr Medvedev), who sneakily reinvents the play.

There are pleadings with the patient, liberal warden (Marina Hands), repeated struggles for Jordan as he memorises Lucky’s three-page monologue, and a superfluous subplot concerning Etienne and his daughter.

Mostly, however, these are faux-impediments in an unabashedly feel-good film that hits all the regular beats of the superstar teacher subgenre. Is there a scene in which the prisoners call out to other inmates for a grander moment of group catharsis? Of course. Will the authorities relent when the troupe is asked to perform the show on tour? Indeed. Does the tough guy prove to have a softer side? Bien sur.

For all the predictability and slightly thin plotting, this is an irresistible confection of heart, good-humour, and likable performances. It hardly matters that it’s slightly undercooked.