When Robert Plant started releasing solo material in the early '80s, post-Led Zeppelin, he showed that his wide-ranging tastes lean toward the mystic. His spine-tingling wail—whether backdropped by baroque folk or hard, bluesy guitars—pierces at its peak and rumbles when he roars. Plant's wanderlust sails through the undulating waves of the gentle, string-driven "Song to the Siren", and his soulful delivery on soft rock's "Big Log" caresses like silk. He found the perfect foil in the honeyed coo of Alison Krauss, with whom he recorded an album of alt-country duets.