Reese Witherspoon is roughing it in on a 1,1000-mile solo hike along the Pacific Crest Trail in the first look at Wild, the film adaptation based on Cheryl Strayed’s bestselling 2012 memoir, Wild: From Lost to Found on the Pacific Crest Trail.

Directed by Jean-Marc Vallee, who helmed the Oscar-winning AIDS flick Dallas Buyers Club and adapted to screen by Nick Hornby, Wild follows Strayed, a recovering heroic addict from Oregon who sets out on the ambitious and often treacherous trek at the age of 26 after the death of her beloved mother and a failed, disappointing marriage. The trailer gives us the first look at 38-year-old Witherspoon in the complex role, braving rough lands and even rougher weather, encountering wild animals and facing one life threatening situation after the next—all while also taking in gorgeous, one-of-a-kind views and wondering what the world she got into. The clip also shows Strayed reflecting back on her life and loved ones as she delves deeper and deeper into the hike.

Though Strayed ran into several other brave hikers on her quest (as she explains in her memoir) and even becomes friendly with some of them, the vast majority of the book focuses on her and her alone—as she endures both the physical and mental adversities of a solo journey that forces her to further examine the remnants of her wrecked personal life. That means that Witherspoon will also have to carry the story alone for most of the movie, much like James Franco in the biographical survival drama film 127 Hours.

Though this film marks a clear and definite departure from the comedic roles Witherspoon is mostly known for (Legally Blonde, Four Christmases, This Means War), this isn’t her first turn in a biographical film. She also took on the role of June Carter in 2005’s Walk the Line, a performance that won her several awards, including the Golden Globe, the Screen Actors Guild, and the Academy Award for Best Actress in a Lead Role.

Still, it’s a difficult role to take on for anyone, especially considering how well Strayed memoir performed. The book reached number one on The New York Times bestseller list and was lauded by Oprah for Oprah’s Book Club 2.0.Meanwhile, Witherspoon’s film company Pacific Standard optioned the novel for film rights, with Witherspoon in the starring role, right around the same time the book was published.

News of her casting produced mixed reviews with some fans of the novel wondering whether the actress really had the acting chops to play the determined and self-sufficient but troubled Strayed. Then again, both James Franco and Matthew McConaughey, who recently pulled a career 180 with his performance in Dallas Buyers Club and True Detective, both starred in their fair share of comedies (romantic or otherwise) as well before their critically-appraised roles.

Wild also features Gaby Hoffmann (Uncle Buck, Girls) and Laura Dern. The movie was filmed in different areas all around Oregon, including Ashland, Bend and Crater Lake National Park, which contains 33 miles of the Pacific Crest Trail that Strayed embarked on. It hits theaters on December 5.

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