DEBRA Granik’s first feature film since the Oscar-nominated Winter’s Bone of 2010 has been a long time brewing. Leave No Trace finds her still concerned with modern American tales of survival, but this time she has pared her material down even further to ask what is truly essential to a person’s well-being.

The result is a slow burn drama for which, contrary to its message about travelling through life with as little baggage as possible, you will want to find room.

Grabnik’s tale, adapted from the novel by Peter Rock, opens in a forest. A middle-aged man and a teenage girl are preparing food over a campfire. It is clear from the surroundings that this is no mere weekend trip. They have made the closest thing to a home as is possible in the outdoors, with everything they need, and nothing surplus to requirements. When the man calls “Drill!” and the pair rush into the forest to hide the viewer’s interest is further piqued. Who are they and why are they hiding from the world?

The whys and how surface at a slow, steady pace. Will and Thom (Ben Foster and Thomasin McKenzie) are father and daughter and they have made their home in a public park. Not the swings and roundabouts and benches kind of park, but one of the vast tracts of land America was wise enough to safeguard for the public.

Will and Thom are not entirely alone. A short walk reveals a work party carving out a trail for hikers. Provisions are a short walk away in town. What to buy is settled by a simple rule: do you need something, or do you just want it?

Town is also where Will picks up his medication from a veterans’ clinic. It is by selling these drugs that he acquires money to live. While this means he has to cope without chemical help, we get the sense that the drugs stopped working for Will some time ago.

The pair’s luck runs out when a jogger catches a glimpse of Thom, peeking out on “civilisation” as if she wanted to be seen. The authorities duly rock up. It is illegal to live on public land. Moreover, the pair’s living arrangements, isolated, living in one tent, set alarm bells ringing with child services. The same obvious concern is quietly raised at other points, and dealt with swiftly. The characters are so strong and rounded from the outset that the audience is left in no doubt that there is nothing untoward here. Having already lost the girl’s mother, this is a family determined to stay together, whatever it takes.

But what does it take? What do you need in life and what do you want? These are the questions Granik’s picture raises over and over.

After a rocky time, the pair look to have found a place of their own. Thom thrives, relishing the changes. “I think it might be easier for us if we try to adapt,” she tells her father.

Will, though, seems more distressed with every day they stay put. At the same time he can appreciate how difficult life has been for his daughter. Stay, go, want, need: the questions are obvious, the answers less so.

Particularly since so many people seem to want to accommodate Thom and Will. Their path to a settled home is made easy, perhaps too easy. It is nothing but kindness and understanding wherever they go. At other times the film’s strongest point, its subtlety, is unwisely cast aside, as when Thom shows her dad a beehive and urges him feel the warmth rising from it. We get it.

Such faults are easily forgiven. Leave No Trace does require the suspension of cynicism, but it rewards the effort. Both Foster and McKenzie are superb. The last time a father-daughter pairing was this successful was Paper Moon, where Ryan and Tatum O’Neal had a natural advantage. Foster and McKenzie spark the same chemistry through their combined acting talents, an achievement made more remarkable given how little dialogue there is.

But that’s Leave No Trace, a film where less is defiantly, definitely, more.