A confusion of genders: "Tomboy"

The French director Céline Sciamma appears to have made it her business to scrutinise that no-man's-land between childhood and womanhood, a life-moment when everything is, one way or another, up for grabs. Sciamma's debut, 2007's Water Lilies, charted the rivalries and jealousies floating around within a teenage girls' synchronised swimming squad; her follow-up Tomboy centres on a pre-pubescent sprite who's moved to a new home and school at the precise moment they've grown to be unsure of their own body. Wiry and flat-chested, the youngster is introduced as Mikael, whose athleticism wins the admiration of teammates in impromptu kickabouts, and the renewed affection of a younger sister, who takes to referring to Mikael as her big brother; Mikael also wins the adoration of the girl next door, who senses he's something special. Special, indeed, for Mikael (Zoé Héran) has a secret: her real name is Laure.

As Water Lilies suggested, Sciamma falls into a long tradition of directors-as-anthropologists: while the grown-ups who play mum and dad are clearly acting, it's possible the child performers have just been instructed to play before the camera, to respond to the environment into which they've been set. Time and time again, Tomboy returns to the sight of these youngsters testing out their own bodies, in rough-and-tumble fieldsports, or testing the limitations of others, in games of truth-or-dare where the participants merrily confess to tasting their own excretions. There's also something of a documentarist like Nicolas Philibert in the way Sciamma patiently observes these kids, an approach that felicitously happens to mesh with the description of adolescence as a time when you feel everybody's watching you, to see which way you're going to go, how you're going to turn out.

Sciamma takes rather bolder risks, for all that. Despite the U certificate, the manner in which Mikael is revealed to be, beyond all doubt, a Laure may well have given the censor (and may well give the perhaps overly sensitive viewer) pause for concern. (To set it in a cinematic context, it's the scene that went towards The Crying Game's 18 certificate, albeit in the rather more wholesome context of the family bathtub.) Either way, it would be difficult to imagine a male director being allowed to submit a young female actress to this level of scrutiny, or indeed being so sensitive and perceptive in the process of making such observations: Sciamma spots the restlessness in her heroine, the traces of incipient self-loathing, the puzzlement of someone not as yet old enough to figure themselves out.

Yet the director remains young enough to remember the undoubted pleasures of being young: the tearing through the woods on afternoons that stretch out like the centuries, the scent and texture of Play-Doh. It's a perfect tying together of deep-rooted anxiety and childhood ingenuity that Laure should use the popular plasticine product to fashion herself a mock-penis, to slip in her swimming trunks when her friends invite her to a lake; and one scene of dancing to pop music in Laure's bedroom is unutterably lovely. Sciamma is turning out to be as much a screen sensualist as Claire Denis, equally in thrall as she is to the possibilities of the (here inchoate) human form.

My only slight reservation with Tomboy is the altogether safe, slightly bland environment the filmmaker conducts her studies within: able to confide in a loving father and nurturing mother, Laure has at least one advantage over the crossdressing pre-teen of 1997's Ma Vie en Rose, which offered a somewhat more credibly shaded and harassed backdrop for the protagonist to have to define themselves against. All in all, though, Tomboy is another small step forward for one of France's brightest emergent talents: a film that engages with all manner of complex gender issues even as it renders sweet and enjoyable homage to the joys and confusions of youth.

Tomboy opens in selected cinemas from Friday.