The film begins with Cheryl pulling of the toenail of her left big toe. She loses one of her boots and screams into the vastness as she throws her other boot down the side of the mountain. We flash back to learn that Cheryl has just begun her journey of one thousand miles on the Pacific Crest Trail. Her hiking pack she carries is bigger than she is, but she manages to find a way to put it on her back and begin. She discovers that she has brought the wrong kind of gas for her to cook with and is unable to cook food. After a few days of hiking she comes across Frank, a man working in the fields and he takes her to his home where he and his wife feed her a hot meal and give her a place to shower and rest.
Back on the trail Cheryl meets a hiker named Greg who is much more experienced. They plan to meet at Kennedy Meadows. Once there she meets Ed, a camper who helps her to lighten the load of her pack. Cheryl receives a care package from her former husband and a letter. We learn that they have recently been divorced. Despite Greg telling her that there is snowfall in the route Cheryl wanted to go, she continues on. Before she leaves Greg tells her that her boots are too small and she can call REI and have them send the right size to the next stop for her. Cheryl continues on and this is when she loses her toenail and boots. She treks another 50 miles in sandals before arriving at the next stop where her new boots are waiting for her.
Along her journey we see flashbacks from her life. We learn that she has recently lost her mother, and her divorce was caused by her sleeping with any man who would ask. She was experiencing deep pain from the loss of her mother and only found relief in these nameless encounters which eventually lead to her moving to Oregon with a man and beginning to use heroine. Cheryl receives another letter from her ex-husband and decides it's time to move on and tells him so. We learn that her ex, Paul found her in Oregon nude in a bed with another man after a night of using, and brought her back home. She argues with him not understanding why he would come back, his only response is, "because." We see that he loves her deeply and even through the pain she's inflicted on him he wants her to live a full life.
She carries on with her journey and runs out of water. She finds a grimy puddle that she siphons water out of and cleans. While there two hunters come across her path and she helps them siphon water as well. They make her feel uncomfortable to the point that she believes they are going to commit a violent act against her. She runs away scared to her soul of them finding her.
On the next stop Cheryl meets Jonathan while in Oregon and goes to a Grateful Dead tribute he's putting on after the death of Jerry Garcia. They spend the night together. A few days later she meets a few young hikers who know her only by the quotes she has been leaving behind on the Trail markers. She drinks Jack Daniels with them and wakes up after having a nightmare about having to kill her mother's horse after her death. The horse was sick, but was also her mother's solace after leaving her abusive husband, and putting it down haunts her.
Strayed continues on her journey and on a rainy day finds a llama which she wrangles. It belongs to a woman and her grandson who tells Cheryl he has some problems he's not supposed to talk to strangers about. Cheryl tells the young boy she lost her mother recently, and the boy sings Red River Valley to her. After the boy and his grandmother leave Cheryl breaks down crying.
On day 94 Cheryl crosses The Bridge of the Gods on the Columbia River between Washington and Oregon and she sees a red fox which has been following her for a large portion of her journey. The fox looks at her then leaves. Strayed then speaks about four years into the future when she would remarry again in a place where she could see the spot she's currently standing at on the bridge, and five years after that she would have a son and one year later she'd have a daughter that they would name Bobbi after her mother.
