Nobody makes somber sound more exquisite than Alison Krauss. She's come an awfully long way from her days as a teenage fiddle prodigy, as her glamour gown on this CD's cover suggests and the bittersweet maturity of the music confirms. Krauss exchanges her bluegrass fiddle for the chamber strains of viola on much of the material, including four songs by Robert Lee Castleman (whose "The Lucky One," "Let Me Touch You for Awhile," and "Forget About It" were previously popularized by Krauss). Castleman's compositions showcase the emotional intimacy and interpretive subtlety of her breathy trill. The yearning harmonies on "Wouldn't Be So Bad" (written by Gillian Welch and David Rawlings) and "Borderline" (written by Sidney and Suzanne Cox) reinforce the album's restless spirit of quiet desperation. Change-of-pace contributions by Krauss's bandmates are more deeply rooted in the bluegrass/folk tradition, with Dan Tyminski renewing Del McCoury's "Rain Please Go Away" and Woody Guthrie's populist anthem "Pastures of Plenty"; Dobro master Jerry Douglas leads the charge on his instrumental "Unionhouse Branch." Few bands in bluegrass can match the virtuosity of Union Station's interplay, but the artistry of Alison Krauss transcends genre.