This is a music-filled documentary about the search for two forgotten blues singers, carried out in Mississippi during the height of the American civil rights movement. With Guy Clark Jr, Buddy Guy, Common, Lucinda Williams, and others. “A powerful meditation on the origins of an African-American musical genre and the painful reasons for its existence.” -rogerebert.com (Samuel D. Pollard, 2016, USA, 1:20, NR)