Just before the title card of Wild, Jean-Marc Valle’s adaptation of the life of writer Cheryl Strayed, a blur of images flit across the screen. Flashes of nudity, drug use, rough sex, and a life on the street belie the images of Reese Witherspoon, alone on the side of a mountain in the midst of her near 1,200 mile hike from California to the Canadian border. As the four letters hover over a black screen, pulsating with a kaleidoscope of shifting colors, it becomes clear that the word is not just about this woman’s fight against nature, but her fight against her entire life leading up to this point, screaming at the indifference of the world as she hurls her too-tight boots into the valley below.

Strayed (Witherspoon) has gotten to this point out of necessity. Thrown into a spiral of drugs and promiscuity after the loss of her mother (Laura Dern in flashback) and husband (The Newsroom’s Thomas Sadoski), the only way she can find a way out is to undertake this dangerous journey, hiking on foot from one side of the country to another via the Pacific Coast Trail, wearing a backpack she can’t lift on her own and shoes that are a size too tight. Relying on a combination of guts and the kindness of other hikers on the trail, Strayed makes her long, agonizing three month trek of physical and spiritual healing, all the while thinking back to the events that got her to the point that she had to risk her life in order to keep living.

Much of the meat of Wild is centered around procedure. The process of packing and unpacking her various bags. The process of moving from checkpoint to checkpoint and receiving care packages to keep going. The process of freebasing, then snorting, then shooting heroin. The process of constructing a makeshift hiking boot out of sandals and duct tape. The process of writing literature quotes in the logs at each checkpoint. Process is all she has left, and Witherspoon throws herself into this aspect of her character with gusto. As she rages against nature, she is truly raging against herself, a woman who had all the promise in the world and could not handle the loss of her mother and mentor.

This all works not just thanks to Witherspoon’s confident and assured work in the leading role. She gets the lion’s share of screen time, of course, and has serious heavy lifting to do in order to externalize a predominantly internal performance, but much of what allows her to get there is built upon Laura Dern’s foundation. She provides the soul of Wild, the beating heart that simultaneously devastates and motivates, the sort of presence that makes Strayed’s addiction spiral feel earned. This is legitimately some of the best work of Dern’s career, certainly award worthy (though the Patricia Arquette Boyhood juggernaut may be unstoppable this season) and the glue that holds the film together even when all seems at its bleakest, especially as Witherspoon is confronted with a series unscrupulous men who carry out a sort of will-they-or-won't-they dance of potential sexual assault that never loses its potency.

For his efforts, Vallee handles a complex script (from Nick Hornby, who does not write as many screenplays as one would think) with aplomb, and has shown quite a bit of growth as a filmmaker since last year’s disappointingly dull and formulaic Dallas Buyers Club. With constant flashbacks with which to contend, and flashbacks within flashbacks that threaten to lose the string back to the present, the screenplay represents quite the challenge, but Vallee and co-editor Martin Pensa juggle the scenes deftly and clearly, and the audience is never left out in the cold regarding what is taking place. With three timelines to flesh out, it could easily become a tangled mess. Hornby and Vallee make sure that does not happen.

Honestly, the only thing holding Wild back is that delicate balance Witherspoon battles throughout her screen time. Her plight is so internal that it is the sort of characterization difficult to transition from page to screen. Witherspoon does a very good job of actualizing her performance into something both convincing and memorable, but her Strayed is always a little beyond arm’s reach. The audience cannot quite empathize with her on the level they do her mother. It is not a flaw of Witherspoon’s performance, or a case of overreach from Dern, but simply the by-product of the sort of character she is. This distance makes Wild work slightly better as an intellectual pursuit than an emotional one, and it does hold back the film from reaching the ecstatic peaks at which it sometimes grasps. It is an accomplished film, surely, but one that also is more of a hint at what could have been.