Reese Witherspoon goes on a hike through the PCT. Through flashbacks you learn that she is on the PCT because her character's mother died of cancer at a fairly early age which she doesn't handle well, so as a result of her loss, she got into drugs, cheated on her husband with multiple partners, which led to a stupid horse tattoo and a divorce. She had a brother as well, but I don't know how he handled the death of their mother as it wasn't his story so that wasn't included.
Overall, I understood what the movie was trying to do, but it didn't pull it off well. I understand why certain actors in this film got Oscar noms, but after seeing the movie, I can see why they didn't win. The film definitely showed how dangerous hiking can be, especially for the uninitiated, underprepared/overly prepared with the wrong gear and extra weight, with the added fact that the main character was hiking alone and was a 22 year old women. Unfortunately the most interesting part of the main character's life was before the trail and done in flashbacks so the audience got pieces of interesting story elements with a lot of foreboding trail elements that didn't bear fruit.