In terms of material, the book has been condensed. It’s worth noting that feature-length films often pare away material as novels typically hold enough raw material to fill more than one film of average feature-length. In this case, Cheryl’s older sister and her stepfather were left out of the film, as well as many of the interesting encounters described in the book (partly because there were so many of them). Certain elements also were given little screen time compared to how many pages were dedicated to them in the book, most notably Cheryl’s relationship with the drug addict Joe. However, it’s worth noting that the film does retain the structure of the original book, which moved back and forth between Cheryl’s history and her hike.