According to a new book, former AC/DC lead singer Bon Scott was nearly fired from the group back in 1975 after he almost died from a heroin overdose.

With so many band breakups, makeups, lineup realignments and tragic deaths taking place throughout the years, there are precious few absolute givens in classic rock history, but Scott’s secure standing as AC/DC’s lead singer until his tragic death in 1980 has certainly been one of them.

At least until recently, when reliable sources as diverse as Clinton Walker’s authoritative Scott biography, ‘Highway to Hell,’ and estranged early-days bass player Mark Evans began chipping at the carefully scripted official band history.

Evans, in particular, obtained a rare insight into AC/DC’s internal politics and the Young brothers’ dominant role within the organization during his three-year tenure in the group, and then shared it in his acclaimed 2011 biography, ‘Dirty Deeds: My Life Inside / Outside of AC/DC'

But as Evans reveals (as quoted in The Australian) in a new book by Jesse Fink, ‘The Youngs: The Brothers Who Built AC/DC,’ not even frontman and co-songwriter Bon Scott was deemed irreplaceable -- not after his death, as proven by Brian Johnson’s successful integration into the group, nor at the start of the band’s inexorable climb towards stardom.

It was during this uncertain period that Evans alleges Scott nearly met his maker AND received his walking papers, after suffering an accidental heroin overdose in 1975. That event, somewhat understandably, elicited concerns about his reliability in the pursuit of AC/DC’s career goals.

As Evans related to Fink, "It was all [kept] very in-house. It was just something that filtered through the band: that things weren't looking good [for Bon]. There was mention of another singer. But it never got to that point.”

Luckily, Scott’s talents saw him through to another chance, and while his nose for misadventure ultimately led to his demise, some five years later (and there has been increasing evidence suggesting heroin -- not alcohol, as has long been claimed -- was to blame for that, too), the rest is of course history.

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