THE ROOTS Undun [Def Jam] The latest from hip-hop’s hippest band is a concept album that tells the fictional—although all too believable—story of Redford Stephens, a low-level street hustler who makes all the wrong choices on his way to an early end. That’s not giving anything away: The Roots tell this story in reverse, rewinding Stephens’ life through songs carefully constructed to avoid glorifying his brief and unfortunate time in the...