McKenna Berney and her best friend, Courtney, had it all figured out: They would defer their college acceptances for a year and dedicate the next six months of their lives to a once-in-a-lifetime exploration of the Appalachian Trail, just as her father and his best friend had once explored the Pacific Northwest Trail. But when Courtney bails at the last minute in order to nurse her failing relationship with her faithless, on-again, off-again boyfriend, it seems as though McKenna’s long-held dream will remain just that. Unwilling to sacrifice months of meticulous planning and preparation, McKenna decides to forge ahead, deceiving her parents and striking out on the trail alone. What begins as a solo expedition quickly transforms into something else entirely, however, as McKenna spends increasing amounts of time with the mysterious and enigmatic Sam, a boy who seems to have made the trail his home. As the two continue to grow closer, Sam and McKenna will test the boundaries of their relationship and their abilities as one fateful decision forces McKenna to confront the one potentially-fatal possibility she never planned for.