They’re back! One of the greatest collaborations of all time, the musical mind-meld of Robert Plant and Alison Krauss, is happening once again on their new album, “Raise the Roof.” Here they are performing the first of two songs for The Late Show, this is “Trouble With My Lover.” Tune in tonight to see them perform a second song from the new album, which is available everywhere today! | The Late Show with Stephen Colbert