After years of playing a dispiriting game of musical chairs with various lead singers during the early '80s, Black Sabbath guitarist Tony Iommi finally stumbled upon a dependable frontman when he admitted relative unknown Tony Martin into the fold, thereby initiating the original heavy metal band's long awaited return to respectability -- if not chart-topping success.

Martin joined the oft-interrupted sessions for what would become 1987's The Eternal Idol album already in progress, stepping in for an unreliable Ray Gillen when the latter moved on to Jake E.

Lee's Badlands, and helping Iommi rescue an astonishingly solid long-player from the jaws of complete and utter chaos.

As it turned out, Martin's powerful, muscular voice -- though bearing more than a passing resemblance to former singer Ronnie James Dio -- was ultimately the perfect foil for full-bodied heavy metal anthems like "Hard Life to Love," "Glory Ride," and "Born to Lose," which were built upon some of Iommi's heaviest, most undeniable riffs of the decade.

A hodgepodge of temporary backing musicians and short-lived producers somehow manage to fill in the gaps, and make The Eternal Idol sound like a very cohesive LP.

If anything, however, it's the ever-reliable Geoff Nicholls who embodies a third pillar of stability, by adding impeccable supporting keyboards throughout -- most notably to "Ancient Warrior" and the fantastically gloomy title track.

And above all else, The Eternal Idol contains a bona fide heavy metal classic for the ages in its monumental opener, "The Shining," which Iommi had been kicking around in demo form since 1984, and which, in its final glorious form, is rightfully considered one of Black Sabbath's greatest songs bar none, regardless of singer, era, or album sales.

In tandem with the consistently stellar songwriting all around, there's no denying The Eternal Idol's standing as quite possibly Black Sabbath's most underrated opus, and arguably their best without either Ozzy Osbourne or Ronnie Dio at the microphone.