Kill 'Em All may have revitalized heavy metal's underground, but Ride the Lightning was even more stunning, exhibiting staggering musical growth and boldly charting new directions that would affect heavy metal for years to come. Incredibly ambitious for a one-year-later sophomore effort, Ride the Lightning finds Metallica aggressively expanding their compositional technique and range of expression. Every track tries something new, and every musical experiment succeeds mightily. The lyrics push into new territory as well -- more personal, more socially conscious, less metal posturing. But the true heart of Ride the Lightning lies in its rich musical imagination. There are extended, progressive epics; tight, concise groove-rockers; thrashers that blow anything on Kill 'Em All out of the water, both in their urgency and the barest hints of melody that have been added to the choruses. Some innovations are flourishes that add important bits of color, like the lilting,