“Wild,” the new film from Jean-Marc Vallée, the Academy Award nominated director of “Dallas Buyer’s Club,” is a road movie. Or rather, a path movie as star Reese Witherspoon hardly spends any of her 1000-mile journey from Mojave Desert to Canada on an actual road.

Witherspoon is Cheryl Strayed, a literate young woman whose life spins out of control after a family tragedy. To ease her pain she steps outside of her marriage to Paul (“The Newsroom’s” Thomas Sadoski) and into a world of booze, drugs and anonymous sex. She calls herself an experimentalist—the “girl who says yes instead of no”—but when she hits rock bottom she runs away from the past toward an uncertain future, cleansing herself and her soul with a 1000-mile trek on the Pacific Crest Trail. “I’m obsessive,” she says, “but this is stretch for me.”

Most road movies are linear. They start at point ‘a’ and by the time the main character is at point ‘z’ they have undergone a spiritual journey as well as a physical one. In “Wild” Cheryl moves continuously moves forward but the story jumps to-and-fro with flashbacks to her childhood and drug fuelled past. The fractured timeline supplies an impressionistic look at Cheryl’s life, as though we are sifting through her memories, looking for clues as to why she ended up on the trail.

It’s a dreamily effective way to tell her story. Filled with happiness, pain, sorrow and more melancholy than a Patsy Cline ballad, it feels like a life on parade. Like puzzle pieces the snippets piece together to eventually form a whole.

The story of Cheryl’s physical survival—too tight boots, toenail trauma, dehydration—is less interesting than her quest for emotional survival. Witherspoon is best not when she’s fumbling with a bowl of “cold mush” or a broken propane heater, but when she puts herself “in the way of beauty, to become the woman her mother (a terrific Laura Dern) said she could be.” Mom told her to “find your best self and hold on to it,” which is not only good advice but also gives Witherspoon the chance to dig deep to find the character.

She can play the comedic bits—struggling with a backpack twice as big as her and being mistaken for a “lady hobo”—but it’s the sensitive stuff that hits home here.

It’s too bad that the movie, in its last thirty minutes, doesn’t trust the audience to process what it just saw. Near the end spirit animals appear and Witherspoon’s narration recaps her journey. Unless you walk in during the movie’s last act you already know everything about the journey and don’t need a summary.

Luckily the last few minutes also contain a scene so strange and emotional it rescues it from tipping over into sentimentality. Walking along the path, almost at her destination, Cheryl encounters a young boy and his grandmother. After some conversation the lad sings a verse or two of “Red River Valley” and provides the movie with one of its quietly emotional highlights.