Eastern Kentucky, 1937. After the death of her husband, Ada Donovan returned home to live again with her aging parents. She does all she can to help them keep the small family farm going. But times are hard, and there's never enough. During one of her infrequent visits to town, she sees a help-wanted notice for the Pack Horse Librarian Project, seeking librarians to ride up high in the mountains and bring books to the people there. Before her marriage, Ada was a teacher, and the thought of returning to the work she loved is impossible to resist. The mountains are her favorite place, books are her great joy, and her horse is her best friend.But not everyone on the mountain is happy to see her.Living in a crumbing cabin at the highest, most isolated point of Ada's route, there's a family that catches her attention. The father keeps to the shadows. There is no mother to dote on the happy, curious children. But soon Ada comes to love them just as fiercely as the woman they lost.And makes it her mission to bring them the world.