The first four songs on Unchained come from the songbooks of Beck, Don Gibson, Soundgarden, and Jimmie Rodgers. What might look like absurdly unsupportable eclecticism in other artists, of course, is pretty much standard stuff for Cash. Unchained is hardly standard, though; it's more like the best album he's made since his 1984 departure from Columbia records. Not only is this a stack of songs perfectly and idiosyncratically suited to the man, they're given door-rattling backing treatment by Tom Petty and the Heartbreakers, who prove as fitting for Cash's music as his own Tennessee two was back in the day.