Though sometimes an uneasy watch, it's right that Nora Fingscheidt's System Crasher comes with no easy answers. It follows Benni (Helena Zengel), not yet ten and already testing the limitations of German social services, as she is passed between the few group homes still willing to take her. She desperately wants to live with her mother Bianca (Lisa Hagmeister), who loves her but is not prepared to look after her. An early, illuminating sequence shows Benni conning her way back into the family home where her younger siblings are alone, watching TV; when their mother eventually returns with her boyfriend, Benni and her sister visibly flinch at the sight of him, and the volatile Benni turns violent.

Her PTSD – or perhaps her dreams – are signified by a curious, though not ineffective, aesthetic of flashes of hot pink, accompanied by numerous hazy jump-cuts. The energy of the film's score, pacing and cinematography reflects Benni's own restlessness. Although Benni's rage and obvious trauma are notable, she is brilliantly complex: observant, manipulative – but never maliciously so – and prone to giggles when amused. She's so charming that her case worker, the sympathetic Maria (Gabriela Maria Schmeide), and her former foster mother Silvia (Victoria Trauttmansdorff), are clearly endeared to her, as too – increasingly – is Micha (Albrecht Schuch), a brooding school escort with anger management issues of his own. Briefly, it seems he may have a treatment solution for Benni, but that too creates new challenges.

While Zengel is a revelation, she's propped up by a fine supporting cast, each afforded plenty of nuance by writer-director Fingscheidt's characterisations. Primarily a documentary filmmaker, Fingscheidt spent several years researching and familiarising herself with the German care system – almost frustratingly, her film castigates no one, recognising that these issues are hugely intricate. It's a stressful, draining experience, but undoubtedly worthwhile.

Available to watch on Curzon Home Cinema from Fri 27 Mar.