Robert Plant’s affection for roots music continues on this collaboration with bluegrass superstar Alison Krauss. Together, with producer T Bone Burnett, they explore a variety of roots styles, from the swamp blues of the opener, "Rich Woman," the pedal-steel fueled sorrow of "Killing the Blues" and quiet county desperation of Gene Clark's "Polly Come Home" to the lonesome despair of Townes Van Zandt's "Nothin'."