Mention the name Robert Earl Keen, and several descriptive terms spring to mind - Texas singer-songwriter, career artist, brilliant storyteller, sardonic humorist, poet of the strange and familiar. And now with the release of his latest album, Happy Prisoner, there is what may seem a surprising addition to that list - bluegrass singer. Kicking off with a boot-stomping version of Flatt & Scruggs "Hot Corn, Cold Corn" and revved-up, fiddle-driven take on Richard Thompson's girl-meets-boy-meets-motorcycle tale "52 Vincent Black Lightning," Keen takes us on a ride that embraces the many lyrical and musical colors in the bluegrass spectrum. There are prison songs ("99 Years For One Dark Day"), murder ballads for the guilty and innocent ("Poor Ellen Smith" and "Long Black Veil"), tales of unrequited love (a lilting cover of the Carter Family's "East Virginia Blues"), gospel tunes ("This World Is Not My Home"), yodelin' tunes (a joyous duet with Lyle Lovett on Jimmie Rodgers' "T for Texas"), waltzes (the mournful "White Dove") and songs of country life (a gorgeous take on Tommy Thompson's "Twisted Laurel"). And of course, there are special nods to the father of bluegrass Bill Monroe ("Walls of Time" and the moving "Footprints In The Snow").