On the surface not much happens in “Leave No Trace,” at least in terms of incident, and what little does, unfolds very slowly and quietly. Beneath the apparently placid exterior, however, much is occurring in Debra Granik’s long-gestating follow-up to “Winter’s Bone,” the picture that launched Jennifer Lawrence’s rise to stardom in 2010, and though some of it remains enigmatic and unspoken, this perceptive, deeply humane film will certainly belie its title and linger in your memory.

Adapted by Granik and co-writer Anne Rosellini from Peter Rock’s novel “My Abandonment,” the film begins with widowed military vet Will (Ben Foster) and his daughter Tom (Thomasin Harcourt McKenzie) living in a heavily-forested park outside Portland, changing their camp frequently to avoid detection and engaging in drills to hide in case outsiders should come upon them. We watch as they go about the business of growing food, collecting rainwater and maintaining a semblance of shelter, or occasionally walk into the city to allow Will to collect his prescribed VA medications, which he then sells to other homeless people for the cash he needs to buy the few necessary items they can’t make for themselves.

One day a park worker spies Tom, and soon a passel of cops arrives with dogs to track her and Will down. A concerned social worker (Dana Millican) and her associates put them through a battery of psychological tests and decide to find them a permanent place to stay: a house at the rural Christmas tree farm owned by a gruff but sympathetic rancher (Jeff Kober), where Will will work while Tom goes to school. Tom begins to like the sense of stability—even a visit to church on a Sunday morning, where the assembly is treated to a performance by an unorthodox dance troupe–especially after meeting a neighbor boy (Isaiah Stone) who introduces her to 4-H meetings, but Will, troubled by his post-traumatic stress disorder demons and hardly suited to a job that involves cutting down trees, insists that they pack up and leave.

Getting a Lift from a trucker, they wind up in a frigid woodland where they are fortunate to find an empty hunters’ cabin that they break into and use as refuge from the cold and damp. Tom stays behind while Will goes out to find supplies, but he’s injured on the trek, and only Tom’s fortuitous stumbling upon a group of marginalized folks who have established a community for themselves in the wilderness saves him. Installed in a trailer by the kindly leader of the group (Dale Dickey), Will recovers. But as his leg heals, his distinctly unromantic wanderlust returns, and he’s driven to move on. By now, however, Tom wrestles with whether to go with him.

In terms of genre, “Leave No Trace” is essentially a coming-of-age story, in which Tom, played by McKenzie with a remarkable degree of understatement, struggles to free herself from carrying the burden of her father’s psychological baggage—a painful process for the girl. But Will is in no way portrayed as a villain. Foster can give performances of such visceral intensity as to be positively frightening—his turn in “Hell or High Water” is perhaps the best known of those in which he portrays a perpetually angry man always on the verge of exploding—but here he is subdued and reflective, though always with a hint of danger—and inarticulate suffering—simmering beneath the laconic surface. It is certainly a change of pace for the actor, and one he handles brilliantly under Granik’s supportive direction.

Together with her behind-the-camera partners, Granik also creates a gentle, ruminative mood in which her actors can flourish. Michael McDonough’s cinematography revels in the luxurious green of the forests—and even the visual beauty of the Christmas tree farm—and editor Jane Rizzo emphasizes the atmosphere not only by adopting a deliberate pace but occasionally cutting to foliage being blown by unseen winds. The film also makes use of silence to powerful effect, though Dickon Hinchliffe’s minimalist score adds a note of sadness and yearning at appropriate moments.

“Leave No Trace” takes what might have been a Hallmark Hall of Fame-style story of uplift and treats it honesty, with a sense of empathy toward characters that are realistically complex and difficult to fathom. Together with “Winter’s Bone,” it marks Granik as a filmmaker of rare gifts, and one hopes that the Kubrickian hiatus between these two efforts will not become a habit.