Indie-folk breakouts Mumford & Sons are exploring heavier territory on the follow-up to 2009's smash, Sigh No More. "It's doom folk, like Black Sabbath meets Nick Drake," bassist Ted Dwane says of the untitled LP, which is almost done after productive writing sessions in Nashville and the U.K. last year. "We never thought we'd be commercially viable – and we were wrong," Dwane adds. "It's been a great couple of years for the band, and I suppose it has instilled us with confidence."
This story is from the January 19th, 2012 issue of Rolling Stone.