★★★☆☆

Living out in the woods, cabin schooling your children and strict SAS-style survival regimes constitute an unorthodox existence. But with its championing of independent thought, outside the box parenting and fervent anti-establishment ethos Captain Fantastic may just convince you it’s a worthwhile idea. More Fantastic Mr. Fox than Captain America, it is a quirky, enchanting study in alternative living, self-truth and grief which is at its best when existing outside the sphere of ‘the real world’.

The head of a brood of ginger-haired, highly disciplined whizz kids is Viggo Mortensen’s Ben. In the opening (and strongest) third, that occurs in a breath-taking North American wilderness largely out of time and specific place, he and uniquely named children Bodevan (George MacKay), Kielyr (Samantha Isler), Vespyr (Annalise Basso), Rellian (Nicholas Hamilton) and Nai (Charlie Shotwell) spend their days hunting, training and conducting chores in a grueling but harmonious routine. There may be quite a gaggle of them but each is well sketched with individual traits and idiosyncrasies which are a pleasure to behold. Nighttime campfires begin with the children ingesting non-fiction on the cosmos, warfare and politics – Mao, Trotsky, Marx and Stalin are household names and the youngest of their midst has a shrine of animal skulls for Pol Pot. It may all sound rather pretentious and showy but the script is tight.

However, the absence of an adult female influence is keenly felt and it soon becomes clear that not all is well in paradise. The children’s mother, Leslie (Trin Miller) – who will appear only in dreamlike fragments as Ben wakes from sleep – suffers with mental illness and has been hospitalised somewhere out in civilisation. A scene in which Ben relays news of her suicide to his children is emotional wrenching and very well handled but grief is not given enough attention thematically. Told to stay away from the funeral by an officious father (Frank Langella), who threatens to have Ben arrested, one and all jump defiantly into ‘Steve’ – a converted Greyhound bus – and hit the road for New Mexico. Run-ins with a cop, regular Americans – “Everyone is fat like hippos!” – and Bo’s first cringingly awkward crush induce moments of real humour but it’s a pity that Captain Fantastic plateaus in the latter stages of its journey.