Having become international metal heroes with The Number of the Beast and Piece of Mind, Iron Maiden tested themselves with 1984's Powerslave. The band's fifth album is lyrically and musically complex without ever tipping over into Spinal Tap-style self-indulgence. Opener "Aces High" throbs with brutal intensity, while the 13-minute epic "Rime of the Ancient Mariner" hints at the conceptual weight and instrumental complexity to come in the band's late '80s work. This is Maiden at their most powerful and uncompromising.