Before Brandi Carlile was a folk-rock superstar, she was a high school dropout spending her time in a lakeside shed with her first real band, which comprised Carlile, her brother Jay, and a pair of thirty-something locals from Carlile’s native Washington State. Carlile’s teenage years days were full of uncertainty and exploration: In just a few short years, she would begin gigging relentlessly around Seattle and meet her future musical collaborators, the Hanseroth Twins. But before then, she spent much of her time narrowly avoiding trouble with siblings Jay and Tiffany,...