Four years after she charted the birth of the women's vote in Suffragette, filmmaker Sarah Gavron returns with a more intimate but no less essential exploration of the female experience. Ideas of emancipation, identity and pushing one's own limits reverberate in this richly-textured story of a modern London teenager forced to grow up before her time.

Newcomer Bukky Bakray displays astonishing natural talent as 15-year-old Nigerian-British protagonist Shola – aka Rocks – who lives with her mother Funke (Layo-Christina Akinlude) and younger brother Emmanuel (a scene-stealing D'angelou Osei Kissiedu) in East London. When Funke disappears, leaving only an envelope of not-enough money and an apologetic note, Rocks attempts to look after herself and Emmanuel. While she initially coasts by on self-confidence and the support of close friends, she soon finds herself in over her head and running out of options.

While Rocks and Emmanuel's journey, literal and thematic, is the engine of this narrative, the depiction of female relationships is at its heart. That Gavron and her team spent much time with their young cast, with whom they built the story from the ground up, means that this portrayal of teen friendships is frequently funny, deeply moving and always bracingly authentic. There are glorious echoes of Céline Sciamma's Paris-set Girlhood throughout: in the boisterous shouts that introduce us to the girls before we see them; in dance scenes where they let loose with abandon; in moments that vibrate with hope and potential, and those in which reality cuts coldly to the bone.

As with Sciamma's film, location is key. The London skyline looms on the horizon, always there but out of reach, the girls often hemmed in by tiny bedrooms and classrooms. Crucially, however, Rocks is not defined or limited by her tower block home – she has far-reaching ambitions that she is determined to pursue. Her friends, too, come from a variety of cultural backgrounds, each with their own dreams, but they are unquestioningly accepting of each other.

Indeed, the key message here is that, even as traditional support networks of family, school and external organisations are being slowly eroded, girls such as these have always been busy building each other up. 'Real queens fix each other's crowns,' shouts a bedroom wall sticker early in the film; it's a neat encapsulation of the sense of solidarity which makes Rocks such a joy.

General release from Fri 18 Sep.