Director Debra Granik's second feature, 2010's Winter's Bone, was by no means free of problems, but it was a striking, singular kind of trip to a lonely, isolated part of the United States, captured with sympathetic realism and artistic stylisation both. Between its intrinsic merits, its gratifyingly out-of-character Best Picture nomination at the Oscars, and its critical role in furthering the career of Jennifer Lawrence, I would have assumed that the film would have been all the calling card Granik needed, and yet it's taken eight full years for her to finally make a follow-up in the form of Leave No Trace, with the gap filled only by a 2014 documentary, Stray Dog (which I haven't seen, but just the logline makes it sound like a spiritual precursor to Leave No Trace). The wait has been worth it: though Leave No Trace is even less free of problems than Winter's Bone, its shares that film's artistic strengths, and its curiosity about the lives of people living so far at the fringes of American society that it barely counts. And once again, Granik has demonstrated an extraordinary affinity with her actors, known and unknown.

The unknown this time around is New Zealand-born Thomasin Harcourt McKenzie, 16 years old at the time of filming and convincingly playing young. The known is Ben Foster, who has been one of the most reliable American actors of his generation over the last decade for bringing a vibe of hushed, melancholy naturalism to his performances, though he's rarely been more melancholy or naturalistic, and never more hushed, than as Will, father to McKenzie's Tom, with whom he lives as a squatter in a large forest preserve near Portland, Oregon. Over the course of the film's none-too-hurried 109 minutes, the pair will be chased out by the police and placed into a relatively stable situation on a Christmas tree farm, which is still too close to civilisation for Will, though the more that Tom gets to know of things like "roofs" and "beds" and "being dry more often than not", the more she starts to long to settle into something more like a household, even if she apparently shares her father's conviction that mainstream culture isn't the way to go.

The film's best aspect and its most frustrating aspect are very nearly the exact same thing, so it makes sense to discuss it upfront: this is an extremely subtle movie (made even more subtle, apparently, by Foster and Granik working together to see how few words they could have his character speak over the course of the movie). Obviously, it's always a good thing when a movie feels like it can trust its audience enough to break away from the standard Hollywood "repeat everything three times" model and just show characters inhabiting their lives. It takes exemplary performances to make that kind of thing work, and Leave No Trace has those: Foster is at or near his career peak, and while McKenna isn't quite as fully-formed as Lawrence was in Winter's Bone - there are at least a few places where she relies on her gigantic, inquisitive eyes to do all her work for her - she offers an extremely sturdy foundation for the entire film to rest upon, and the mere fact that it doesn't crumble entirely is testament to her skills. The entire film is filtered through Tom's perspective, and it is also about Tom's gradual growth in understanding, so the lead role is both the audience's surrogate but also the main object of the audience's study: it's a complicated, though thing to be, and Granik & co-writer Anne Rosellini (adapting Peter Rock's 2009 book My Abandonment) do not leave any space for cheap appeals to audience sympathy.

So anyway, the film exists almost entirely in silences and ellipses: we learn about Tom and Will from watching their behavior towards nature and each other, and this is at times enormously exhilarating, particularly in the very earliest parts of the movie, when Granik's approach is most documentary-like, sort of like an ultra-realist Malick film as she and cinematographer Dickon Hinchliffe soak in the grey-streaked greens and browns and blues of the Oregon woods, while the characters prepare fires, waterproof their lean-to, and all the other things one must do if one is going to try and live out in the wild. At its best, the film manages to evoke both the romantic appeal of this lifestyle and the backbreaking, all-consuming labor it takes to sustain it, steadily refusing to come down on the question of whether Will is making Tom a more self-sufficient, intelligent person, or destroying her ability to function like a 21st Century human to suit his own whims. Often, it doesn't even seem to recognise the question, preferring instead to focus on what is: it is a film constantly aware of the ongoing present, and the way that the characters' lives are constantly focused on getting through this moment, this problem.

The downside of all this is that it's not exactly what Leave No Trace fancies itself to be, I don't think. This isn't a documentary, after all, not even an especially artful, graceful documentary full of the most beautiful woodland cinematography in many a day. It's a character study, and the more that it starts to invest in its plot, the more it starts to matter who Tom and Will really are, and what drives them. Particularly as it approaches its ending, which rather sensibly recognises that there's no satisfying way for the situation it has defined to resolve, and so it goes for for the most authentically, plausibly unsatisfying resolution it can manage.

And here's where the dark side of subtlety comes into play. The film is basically all about Tom's changing understanding of her relationship to her father, and the situation that he has put them in because of his very specific, very tortured relationship to the modern world. And the thing is, Will is kept blurry throughout. We learn things about him almost entirely through abduction: his tension when hearing a helicopter, his trips to the VA to pick up psychiatric medication that he then sells, a newspaper headline Tom finds in his belongings somewhat late into the film. So a picture emerges: he has PTSD from his experiences in Iraq, and he's found some measure of solace from his suicidal thoughts by abandoning all of civilisation to go live in the woods. But this is absolutely the only thing we ever learn about him, if indeed we "learn" it rather than making educated guesses. And while this might well serve the mission of psychological naturalism, it's much less successful at serving the mission of drama: what Will gets out of his unconventional life, what he feels about dragging Tom into this, how tormented he actually is by his attempts to live like a good boy in a house, why he makes the decisions he makes in the last 30 minutes, whether there's paranoia on top of everything else: these are all questions the film leaves unanswered and probably unanswerable, and they're all questions that speak to the central issue of the film, which is the daughter-father relationship. As a result, there's an acute hollowness in Leave No Trace: it is amazingly good at capturing the external aspects of the characters and it can only gesture towards their internal aspects.

That leaves a whole hell of a lot of movie worth watching, mind you - the opening act of the film is some of the most impressively haunting cinema I've seen in 2018 - and the film's rejection of any and all bullshit makes for a movie in which any whispers of warmth and sweetness (and there are a good number as it nears the end) feel far more earned. This is nothing like the pandering quirky twaddle of Captain Fantastic, a film that does all the things this one doesn't & does them poorly; it has a rugged, living quality that suggests Granik was hiding under bushes and in closets to record a genuine culture out in the wilderness. Even if it's hamstrung from being its best self, the version of Leave No Trace that exists is a hell of a thing, and much like Winter's Bone, it serves as a reminder of all the amazing things American independent cinema could be if it pushed itself more.