It's not too much to say that in the late '20s the trio of A.P. Delaney Carter, his wife Sara, and his sister-in-law Maybelle changed the course of country - and popular - music. They did it with haunting harmonies, fine guitar playing and a vast repertoire of murder ballads, gospel tunes, love songs, and Appalachian folk melodies which would be covered by musicians for decades.