Reese Witherspoon has a lot invested in ‘Wild’

“Your movie, your movie, your movie!” Laura Linney gushed to Reese Witherspoon, who was brunching at the homey and packed New Sheridan Hotel with her director, Jean-Marc Vallée, and costar Laura Dern the morning after the first public screening of “Wild” at the Telluride Film Festival.

Half the world of international cinema seemed to be at the New Sheridan too — Mexican actor Gael García Bernal, Cannes Film Festival director Thierry Frémaux, Canadian filmmaking prodigy Xavier Dolan and Telluride co-director Julie Huntsinger also drifted over to the table to congratulate the trio, who were discussing the reception of “Wild” over omelets and iced teas.

“I think people don’t know what to expect yet,” Witherspoon said of the film’s opening scene, a shot of her character flinging a hiking boot over a precipice, followed by several rapid cuts of sexual images. “When you have that flash montage, it’s really quick, but it’s, like, ‘Oh, wait, this isn’t a white girl problems movie.’”

“Wild,” an adaptation of Cheryl Strayed’s bestselling memoir about her life-changing, 1,100-mile solo hike on the Pacific Crest Trail from Mexico to Oregon, will premiere Monday for a wider audience at the Toronto International Film Festival before distributor Fox Searchlight opens it in theaters starting Dec. 5.

For actors and filmmakers, a festival premiere is an especially vulnerable moment, a time when critics, peers and audiences might laugh in the wrong places or cry in the right ones, might anoint a movie or demolish it.

The process of sharing “Wild” with audiences is a particularly charged one for Witherspoon, who is playing against the cheerful, girl-next-door persona she established in comedies such as “Legally Blonde” and “Sweet Home Alabama” in a role featuring hard drug use, casual sex and a character confronting a profound sense of loss. Witherspoon optioned “Wild” with her own money, produced its adaptation by Nick Hornby and got so physically and emotionally naked for the role, she said, that she enlisted a hypnotist to overcome her anxiety.

Now she was letting that deeply personal project out into the world.

“Movies have all this potential in your mind,” Witherspoon said in an interview. “Then you make them and it could be anything. It could be the greatest movie ever made or ... you just don’t know. It’s kind of precious and sacred.”

Witherspoon, 38, plays Strayed on her journey to self-discovery, a trip undertaken with a giant pack full of hurt on her back after a divorce and the death of her mother, Bobbi. Dern plays Bobbi, an ethereal figure whom Strayed considers the love of her life.

At 47, Dern is near Witherspoon’s age. Though much of the story unfolds in flashback, they do share many scenes as mother and daughter, with Witherspoon acting as a twentysomething.

“After we did it, we went to dinner with a mutual girlfriend who’s an actor too,” Dern said, adding that the friend asked if, in age-conscious Hollywood, Dern was nervous about playing a character who was a generation older than Witherspoon. “I was, like, ‘Wait, wha?’ It didn’t give me pause before, but after, I felt maybe vulnerable that somebody else pointed it out.”

Shooting the movie took endurance and pluck: To get to the location of the boot-flinging shot, a mountain beside Oregon’s 11,239-foot Mt. Hood, cast and crew had to take two ski lifts and hike half an hour with their gear and a live fox, which appears in the scene. A camera crew was harnessed and suspended off the side of the mountain with belay ropes.

A recurring motif in “Wild” is Strayed’s massive, overstuffed backpack, nicknamed Monster by other hikers on the trail. Concerned with realism, Vallée kept loading down the dainty, 5-foot-1 Witherspoon with weight.

But it was the emotional gravity of the story that both enticed and panicked Witherspoon. She had sought out Vallée as a director after seeing his raw 2013 drama “Dallas Buyers Club,” which earned Oscars for Matthew McConaughey as an HIV-positive electrician and Jared Leto as a drug-addicted transgender woman.

“I didn’t want this to just be a movie where a girl lost herself on a hike,” Witherspoon said. “Jean-Marc doesn’t turn the camera away. We got to set and he said, ‘Let’s talk about the sexuality. I think we need to push it a little bit more,’ and I was, like, ‘Don’t make me do it! Can’t we make Laura do it?’”

One day on set, an extremely thin actor cast as a heroin addict passed out, and a replacement had to be recast in a matter of hours for a particularly intense scene.

“It was, like, ‘Oh, hi, I’m Reese Witherspoon. Nice to meet you. I’m going to take off my clothes now — here’s my leg,’” Witherspoon said. “‘You need to be totally naked, I need to be totally naked, and we’re going to pretend to do drugs together. By the way, we’re four hours behind. So let’s go.’”

Dern said she empathized with Witherspoon’s sense of exposure in the sex scenes, which are played not for their eroticism but entirely from Strayed’s pained point of view.

“As a woman having also done love scenes, you put your vulnerability most often, in my experience, into the hands of a male director,” Dern said. “It’s a very vulnerable partnership. But in this, in every single scene, I only see her longing, like she’s out of her body, her longing to be somewhere else; it just kills me.”

Except for establishing shots of the wilderness, Vallée said, the idea was to tell the story entirely through Strayed’s eyes.

“Most of the film is told from her point of view. What she sees is what we see; what she hears is what we hear,” Vallée said. “The sex scenes were the same. It’s not soft, poetic and sensual.”

Critics at Telluride embraced Witherspoon’s performance, with Variety’s Justin Chang saying that the film’s “blend of grit, vulnerability, physical bravery and emotional immediacy” easily represented the actress’ “most affecting and substantial work in the nine years since ‘Walk the Line.’”

In the film, nature is a vehicle for Strayed’s transformation, so it seemed fitting that “Wild” had its premiere here in the Rocky Mountains, a place where thousands of sweaty hikers and mountain bikers were off seeking their own bliss, oblivious to the film festival unfolding in town.

The morning of the premiere, the “Wild” entourage had taken its own hike together with Strayed, who also was at the festival. It was a chance to reconnect and take a breath before they surrendered their story. At brunch, Witherspoon began hatching a plan for another hike, to celebrate her 40th birthday, on the John Muir Trail.

“It’s almost like we’re the custodians of these ideas, of finding yourself,” Witherspoon said. “We all have been on that journey. It’s just a unique thing to see it from a woman’s perspective. I said to my producer, ‘If we can pull this movie off, it’ll be the first movie that ends with a woman with no man, no mother, no father, no job, no opportunity, and it’s a happy ending. If we can end the movie and she’s just OK, that’s the greatest victory, for a human being to realize, I’m all alone in the world, and that’s OK.’”

Twitter: @ThatRebecca