As the lead singer of Led Zeppelin, Robert Plant seemed invincible, a "Golden God" in the words of journalist/filmmaker Cameron Crowe. Plant may have embraced rock stardom during Zeppelin's zenith in the mid-'70s, but the singer has spent the decades following the band's 1980 dissolution exploring the road less-traveled. Beginning with his 1982 solo debut, Pictures at Eleven, Plant pursued a feverishly adventurous solo career, embracing synthesizers and art rock that seemed to be the antithesis of Zeppelin's majestic hard rock, but he'd also later dabble in sampling and world ...