One of Cash's final and most unlikely hits. This painful ballad was written and performed by super star Trent Reznor. The Nine Inch Nails front man explains why he was reluctant to allow Johnny to record he song in this episode.
Thanks to TheBang for posting this to NIN spotting on echoingthesound.org.
UPDATE: Despite the description, Trent Reznor did not appear in this episode. He's mentioned quite a few times and they show a very old Pretty Hate Machine era picture of him but he's not interviewed at all.