M represents the directorial debut of Sara Forestier, who also wrote the script and stars as the film's female lead, Lila. While her previous work has been impressive, winning awards for projects like The Names of Love, there's no way to avoid feeling that this film is more than a little muddled and uninspired.
Mo (Redouanne Harjane) is an illiterate driver who spends the majority of his time illegally racing cars. Lila (Sara Forestier) is a sensitive writer who struggles with a debilitating speech impediment that threatens her prospects for the future. They are nothing alike except for their perceived brokenness, but this vulnerability creates an understanding between the two that draws them to one another.
M isn't necessarily an original story: man with self-esteem issues begins relationship with equally emotionally fragile woman, only to become maddeningly insecure when said relationship gives girlfriend the confidence and sense of stability she needs to change her life for the better. Now that she is succeeding, he is suddenly terrified that she will realize she can do better and dump him, but instead of communicating with her or doing anything positive, he does pretty much everything in his power to self-sabotage. If he launches an atomic bomb of douche, he doesn't have to face real rejection. Tale as old as time, song as old as rhyme, beauty and the emotionally stunted manchild.
Nevertheless, their frequently combustible relationship makes sense in all the ways that matter on screen, although it is a bit disappointing that neither character is given the depth required for a film that seems like its trying to be a character study.
Mo is the more interesting of the two, as we watch him struggle with feelings of inadequacy over his inability to read and write, and the scenes where Lila's young sister (played by a frankly worryingly precocious Liv Andren) is attempting to help him make sense of French spelling and grammar are definite highlights. (Although the scene where she discovers his secret and he threatens her in very violent terms is less charming.)
But he's also the more frustrating character. His early attempts to force Lila into speaking when she clearly isn't ready come off as boorish and overly aggressive, and his stubborn refusal to ever ask for help is just plain annoying. The well-trod territory of a man struggling to overcome issues of rage and resentment are somehow never quite as interesting as they are intended to be, and in this film Mo's complicated relationship with his mother and sister seems like it is picked up and set down at random, but never truly explored in a way that would give it some emotional resonance.
This is a running theme in the film, where backstory and even entire plot elements are hinted at but then abandoned seemingly at random. The effect of this is to make M feel rather slight and insubstantial. Another issue in the film is the age difference between Lila and Mo. It's a little on the worrying side, largely because it's difficult to tell exactly how old Lila is supposed to be. She seems like a high school student dating a volatile and occasionally emotionally manipulative man in his early to mid 30s, which raises nearly every single red flag in the book.
Overall, M features compelling performances from the two leads, but there are some confusing and borderline uncomfortable choices made that prevent the film from overcoming its shallow plot and bog-standard visual style.