The sun was sliding low over the horizon when Isobel hugged Sierra goodbye, the gravel crunching beneath her tires as she eased out of the driveway. A few days with her sister had given her space to breathe, to cry, to rage—and to listen when Sierra, in her blunt mountain-born way, had asked her the hardest questions of her life.

Her phone lay face-down on the passenger seat, buzzing quiet against the vinyl. At a stop sign on the edge of Pigeon Forge, she turned it over. Dozens of missed ...