Contrary to what the title suggests, this book is not about desire as it relates to human wants. Rather, the title comes from the activity called orienteering, where participants use a map and a compass to navigate from one point to another in unfamiliar territory. According to one of the characters in the book who heads a local chapter of people who engage in orienteering, if one becomes lost in the woods, they can find their way out by following "desire lines," which are faint paths through the woods made by others apart from any established trails. Closely following a desire line should bring you eventually to a safe place.
The premise for the story is that Jennifer vanishes on the night of her high school graduation, just hours after the big event. The last people to see her alive are 5 of her high school classmates. No one knows what happened to Jennifer that night. Now, 10 years later, there is to be a class reunion. Jennifer's best friend, Kathryn, comes back to town, not for the reunion, but to escape her failed marriage and to spend some time with her mother. Since she has some writing experience and talent, while in town, she is asked by the editor of a local paper to investigate Jennifer's disappearance, to interview her teachers and family and friends and see if she can shed any light on what happened to Jennifer that night.
The story isn't so much about what happened to Jennifer (although that issue is resolved by the end of the book), as it is about Kathryn's journey to find out about herself. She has spent the last 10 years basically just treading water in her life, not really knowing where she was headed or what she really wanted. Her failed marriage served as the impetus to take her back to her home town, where she was forced to confront her past (as it pertained to Jennifer's disappearance) and come to terms with what happened. It's more a story of self-discovery than anything else.
But, the story is well-written, the story line is an interesting one, and I learned some things about orienteering, which I never really knew anything about until I read this book.