A beautiful stag pads into a forest clearing dappled with golden sunlight. It’s an Edenic paradise, and all is still.

Then a teenage boy, caked in mud and grime, springs from the bushes and brutally stabs the deer through its heart. As it lies dying at his feet, the beast’s blood is smeared over the face of its killer, a ritual of bloodletting symbolic of his maturation from boy to man.

This is the opening scene of Captain Fantastic.

As you might have guessed, despite the title, Captain Fantastic is not a superhero film. In fact, with its complex and nuanced examination of real-world ethics and morality, it could be argued that Matt Ross’ film is as far from clean-cut fantasy heroics as is imaginable.

The title itself seems to refer to Viggo Mortensen’s character, Ben Cash, who lives an off-the-grid lifestyle with his six children in the Pacific Northwest. However, the film never portrays him in the straightforwardly positive way that such a title implies, instead examining the many pros and cons of his decision to live in this way and the effects it has on his children.

Ben and his family hunt together, meditate together, and undertake gruelling training regimens together, which range from rock climbing to armed combat. In the evenings, they read advanced philosophical and scientific texts and play music around a campfire. It’s a brutal and basic way of life which the film does not glamorise, but for many of us who feel claustrophobically constrained by endlessly scrolling LED screens and breaking news cycles, it looks in many ways preferable to our digital reality.

All is not well in this haven, however. Lesley, Ben’s wife, is being treated for cancer in a hospital far away from her forest home. One evening, she kills herself, and her heartbroken father forbids Ben and the children from attending her upcoming funeral, blaming the lifestyle they chose for his daughter’s death. Unfazed, Ben’s children convince him to defy these orders and attend the ceremony, meaning that for the first time in their lives they are exposed the outside world.

If this all sounds a bit like hard work, be not afeared. At its heart, Captain Fantastic is a sweet comedy drama about the loving bond which exists between a father and his children, and the bittersweet realisation that childhood can’t last forever. What follows is a touching coming-of-age road trip in which we see Ben’s children experiencing life-as-we-know-it with fresh eyes. From discovering hot dogs to pursuing tentative romances, the children find fascination and revelation in all things no matter how small.  Crucially, this broadening of horizons also teaches the children to question their unorthodox upbringing and challenge the authority of their father, whose decision to live a life off-grid has denied them an ordinary childhood.

And it’s not just the children who learn to see things in a new light: as the children gain a taste of normality, Ben discovers the value of compromise and has to accept that his children are growing up and have to be allowed to forge their own paths. Viggo Mortensen is wonderful in this role, giving nuanced performance which embraces the flaws of Ben whilst making it clear that he truly loves his children and simply wants the best for them.

It is in this navigation of Ben’s character that the film really sings: is he a good father trying to help his children by equipping them with real-life skills and an awareness of socio-political issues? Or is he a selfish man-child who never grew out of the hippy counterculture of his youth? It’s a question which the film never gives an easy answer to, instead providing us with a complex and full-blooded character who is instantly believable and defies easy definition.

The Cash children are at times hilarious and endearing, selfish and petty – accurately capturing the turbulent and fractious dynamic that comes with having six angsty teens and tweens under the same roof. George MacKay (who was robbed of an Oscar nom for 1917) is heartfelt and earnest as Bodevan, Ben’s eldest son who is ready to live his own life outside of his father’s ideologies and plays a vital role in the family’s journey towards mutual compromise. MacKay, as in all of his roles, is astonishing here, communicating ideas and emotions simply through his wide and expressive eyes.

All in all, Captain Fantastic is a big-hearted family drama which straddles comedy and tragedy whilst remaining grounded in reality. It’s definitely a bit weepy (especially towards the end!) but has heart and soul in spades and will leave you feeling uplifted – not least thanks to Alex Somers’ sun-drenched score which captures a childish sense of freedom and wonder.

“Captain Fantastic” is available to stream on Netflix.