Over a full decade Black Sabbath had dominated Heavy Metal. As much as Led Zeppelin scorned the term Black Sabbath embraced it. In an age of bona fide super-groups Sabbath were unquestionably the heaviest thing stalking the planet and quite remarkably had remained a solid unit where others around them suffered ongoing membership fall outs and line up re-incarnations. Tony Iommi, Geezer Butler, Ozzy Osbourne and Bill Ward had weathered internal storms just as ferocious as every other band out on the circuit but had remained resolute. They had conquered the globe, sold close to 50 million albums and without concession had not pulled back one iota from delivering absolute, pure Heavy Metal.

In 1977 the unthinkable happened. Ozzy Osbourne decamped. He would be lured back for one last album 'Never Say Die' before flying solo, rapidly building a band unit that would equal the repute of the mothership.

The Iommi / Butler / Ward triumvirate at first bounced back in quite spectacular fashion by re-inventing themselves courtesy of their new frontman, the highly gifted Ronnie James Dio. Two classic albums followed but then the picture shattered. For the next two decades Black Sabbath faltered on a rocky path between all too brief moments of genius and fallow desperation. Only Tony Iommi stuck to his guns, the lynchpin amidst a tangled web of chaos. A succession of vocalists took up the challenge- Ian Gillan, Jeff Fenholt, David Donato, Glenn Hughes, Ray Gillen, Tony Martin and Ronnie James Dio once again.

Harried by the press at every turn Tony Iommi nevertheless succeeded in breathing new life into Black Sabbath time and time again. With the band's back catalogue still in heavy demand those albums crafted in these times of adversity are now recognised as some of Sabbath's finest moments and the huge array of players that travelled through the ranks is now a constant source of fascination and rumours for Sabbath fanatics.

Here, for the very first time with exclusive interviews conducted for this book including with the late Ray Gillen and Cozy Powell as well as the highly controversial figure of Jeff Fenholt and mysterious Dave Donato, is the definitive account of those years. The auditioning, song writing and recording processes of albums such as 'Born Again', 'Eternal Idol' and 'Seventh Star' are examined in depth making this the definitive account.

Author Garry Sharpe-Young is editor in chief at www.rockdetector.com the world's biggest Rock devoted database.