With its Portland setting and unflinching portrayal of living on the fringes of society, Leave No Trace might as well be called Lean On PTSD.

As the alternate title implies, the hardships of Debra Granik’s characters come not from horse racing but via haunted military veteran father Will (Ben Foster) and the disruption of an idyllic yet illegal life in the Oregon woods with his young teen daughter Tom (Thomasin McKenzie, The Hobbit: The Battle of the Five Armies).

Pulled into civilization by social services, the peaceful squatters are asked to adapt to a life that Will never wanted for his child, but which could be a more natural fit for her, setting up a familial conflict that carries the film with varying degrees of success.

The themes of independent existence and thinking for one’s self posit Leave No Trace as somewhat of a non-whimsical Captain Fantastic, though the focus is more on Tom’s journey of self-realization than the struggles facing Will, whose determination to remain an outsider and inability to recognize Tom’s needs — and at times her health and physical capabilities — is a frequent source of frustration.

The pair’s chemistry, however, yields no such issues. Foster, again showing he’s capable of playing more than just psychos, conveys the mental anguish of someone in his position without resorting to clichés, while McKenzie’s natural acting and the way she voices her dialogue doesn’t suggest that she’s on a film set.

Much of the credit for this natural vibe goes to Granik, who crafted a comparable tone with her previous narrative film, 2010’s Ozark-set Winter’s Bone, the energy of which benefited from hillbilly noir elements and a mystery plot to propel it forward.

Despite her follow-up’s similar humane handling of rural folk half a country away, Leave No Trace stagnates a bit too often and never quite hits the next emotional level to which it strives, but is still very much worth a look.

Grade: B. Rated PG. Now playing at Carolina Cinemark. Starts July 27 at Grail Moviehouse

(Photo: Bleecker Street Media)