'God is not listening,' concludes child soldier Agu (the astonishing Abraham Attah) as his ordeal takes a freshly hellish turn. A resident of a war-torn, unnamed West African country, Agu has been taken under the wing of the charismatic, merciless and predatory Commandant (Idris Elba) and his ragtag army, with his happy home but a fading memory.

Based on Uzodinma Iweala's novel, Beasts of No Nation is the latest from Cary Joji Fukunaga, the globe-trotting American director behind Sin Nombre, Jane Eyre and True Detective; and a man who doesn't half know how to make an impression. It's a confrontationally violent and equivalently humane portrayal of life in a volatile country where absolutely everything can be lost in a heartbeat – your family, community and entire way of life.

This engrossing effort hooks you from the off, with Fukunaga restructuring the book's story to quickly cultivate great affection for this self-proclaimed 'good boy from a good family' in warm, witty and relatable opening scenes – most memorably when Agu and his friends attempt to flog a hollowed-out television set to peacekeepers by larking about behind it, an adorable ruse that they dub 'imagination TV'. Such merriment makes the ensuing nightmare more impactful by contrast.

Fukunaga (who also pens the screenplay and acts as producer and cinematographer) is interested in the view from the thick of the action, in the bloody chaos of guerilla warfare and the horrifying human cost of detached political machinations; he illustrates how children's hardship is used to manipulate them as they're ostensibly empowered to fight back.

This is the first foray into film distribution from streaming provider Netflix and, with talk of awards-season recognition well deserved, they've chosen shrewdly. Devastating and dynamic, it's a film that's hard to watch but essential to see.

Screening on Thu 8 and Fri 9 Oct as part of the London Film Festival 2015. Selected theatrical release from Fri 9 Oct and on Netflix from Fri 16 Oct.