In the mid-‘70s, filmmaker James Szalapski documented the then-nascent country music movement that would become known as “outlaw country.” Inspired, in part, by newly-long-haired Willie Nelson’s embrace of hippie attitudes and audiences, a younger generation of artists including Townes Van Zandt, David Allan Coe, Steve Earle and Guy Clark popularized and developed the outlaw sound. It borrowed from rock, folk and bluegrass, with an edge that...