When she lost her beloved mother, Bobbi (Laura Dern), to cancer, Cheryl Strayed (Reese Witherspoon) lost herself, too. Desperate to heal from the self-destructive path that has ruined her marriage and left her a recovering heroin addict, Cheryl decides the best thing to do is to break free from her comfort zone and all the negative patterns that have sent her life spiraling out of control. She doesn't have much experience hiking, which makes the daunting 1,100-mile journey from the Mojave Desert to the Washington state line on the Pacific Crest Trail all the more tempting. If she can survive something so physically and mentally arduous as this, it might be just the thing to finally save her. A tough, soulful adaptation of Strayed's 2012 memoir "Wild: From Lost to Found on the Pacific Crest Trail," "Wild" proves meditative but accessible, a drama both insular and bursting with visual scope. Anchored by Reese Witherspoon's (2014's "Devil's Knot") mightily demanding, wholly immersive performance—arguably her best in close to a decade—director Jean-Marc Vallée (2013's "Dallas Buyers Club") and screenwriter Nick Hornby (2009's "An Education") have turned their protagonist's trek into a seemingly organic sense-memory odyssey of sights and sounds.

The way Cheryl sees it, she has nothing to lose. From an outsider's perspective, it might seem insane for a young woman to say good-bye to her family and friends for what amounts to a really, really long walk. Cheryl knows, though, that something has to change. Never far from the cherished memories of her inspiring mom, whose death four years earlier left an indelible wound that has yet to heal, she fills up her too-heavy backpack, puts on her too-small hiking shoes, and shoves off. She wants to quit after five miles—nay, while she's still within sight of where she started—but she pushes through. Her experiences, from the music she hears to the struggles she faces to the people she meets along the way, take her back to her past. Then again, so does the prevalent solitude of being virtually by herself for several months. Though she is alone with her thoughts, she tells someone late in the film, she somehow hasn't felt nearly as lonely as when she was barely scraping by in her old life.

"Wild," like 2010's "127 Hours" before it, focuses on a single character and their trials and travails in nature. Much in the way Danny Boyle approached that Aron Ralston biopic, director Jean-Mark Vallée avoids all threats of filmic stagnation with a narrative that is emotionally alive and available, free to explore Cheryl Strayed's psyche. Interspersed with meticulously chosen flashbacks that little by little fill the viewer in on our heroine's tumultuous backstory, the film stays by Cheryl's side, observing but not judging. Her little victories, like successfully climbing over a fallen rock blocking her trail or making it to a store that sells the proper white gas she needs to cook on her portable stove, become the audience's, just as the mistakes she makes also do. When a stop in a desolate, wooded clearing sends her into the path of two male hunters, the fear and vulnerability she experiences mounts with almost unbearably still tension. Likewise, when she asks a farmer (W. Earl Brown) for a ride into town so that she might get a warm meal, her apprehension once inside his truck proves unfounded when he invites her over for dinner with he and his wife. The threats she encounters are never far from instances of true humanity, the two disparate sides acting as an unforced metaphor for the good and the bad that life dishes out.

Reese Witherspoon likely would not be the average person's first choice when thinking about casting possibilities for the rough-and-tumble role of Cheryl Strayed, but she doesn't so much as flinch at the difficult subject matter. She not only carries the film, but sells the conflicted, devastated complexity of a character who could never process to swift, bitter, untimely loss of a mother who was everything to her. It helps that no matter what part she is in, Witherspoon is a likable presence one cannot help but care about. As mom Bobbi, who fled an abusive marriage and raised her kids without help from anyone, Laura Dern (2014's "The Fault in Our Stars") is note-perfect as a beacon of love and light viciously snuffed out too soon. It wouldn't have been a bad idea to develop Cheryl and Bobbi's mother-daughter bond even further, but what is offered still gets the point across. Although her screen time is limited, Dern makes the most of it.

"Wild" is gripping and poignant, lensed by cinematographer Yves Bélanger with the textured, natural beauty of its rustic locations. The star, though, is the actor front and center. Despite her Oscar win for 2005's "Walk the Line," Reese Witherspoon is too often disregarded as a lightweight romantic comedy lead when her talent runs far deeper than that. As he did with Matthew McConaughey in "Dallas Buyers Club," director Vallée has gifted Witherspoon with the kind of challenging part that should make naysayers think twice about writing her off. When Cheryl ultimately reaches the end of the Pacific Crest Trail on the suitably named Bridge of the Gods, the anticipated impact of this moment is overshadowed by the dramatically cathartic one that comes right before it. If the ending feels slightly anticlimactic, the rest of the film is on point as it balances dark material with punctuations of levity and hope. Honest, aching and finally uplifting, "Wild" is a human story worth telling.