"If the drums are pounding, the bass is booming, the guitars are rough, and the singer is literally screeching - that's heavy metal!"
Thus begins a 90-minute investigation into the history of a unique phenomenon in music for there is no other genre that so inclusively counts bands all the way from the preened and pretty Skid Row to the dreadlocked distortion of Shadows Fall under its worn, leaking and weathered umbrella.
An ambitious undertaking, Dick Carruthers' film is a chequered, faulty and biased history of the genre, but does nevertheless make for a pretty entertaining watch.
The entire film is far too heavily weighted towards the "Was it Black Sabbath or Led Zeppelin who started it all?" debate, as countless roadies, producers and, er, Dio all state their case with varying levels of authority.
Yes we are all aware that metal owes its history to folks like Jimi Hendrix and Deep Purple, but with the total omission of bands like Slayer and Machine Head, one is left wondering if this film was meant to be a balding rocker's attempt to ensure that the new school paid its dues to the ancients.
This hypothesis becomes more credible by the fact that the film's central interviewee appears to be Twisted Sister's Dee Snider, a man who, incidentally, is incredibly ugly with or without the make up! Spouting off as if he is the newly elected Pope of Metaldom, the only plus is that it looks as though there is now an on-screen figure we can all hate more than Lars "spoilt brat" Ulrich in Some Kind Of Monster.
Annoying focal points aside, there are plenty of charming folks on display here (if you don't warm to Anthrax's Scott Ian and Black Sabbath bass master Geezer Butler, you have no heart!), chapters on the use of particular instruments, production techniques and the age-old link between metal and the Prince Of Darkness (no, not Ozzy - the "real" one!).
Needless to say, with a recounting of the infamous Judas Priest "backward masking" trials of the 1980s and a giggle at the idea that the Midlands' metal legends could actually be "in league with Satan", this chapter is a farce.
So if your favourite bands are missing and you find that the interviews with random second-class icons are a tad dry, at least the sheer amount of extra material packed around the feature should ease the disappointment considerably.
Spread across two discs there is an interactive timeline (which proves considerably more comprehensive than the film), segments where artists recount their favourite ever metal album, while an even lengthier outtakes reel provides enough stories of rock and roll success to send you to sleep. There's even a 10-minute skit of what appears to be a re-creation of Spinal Tap as an LA hair-metal band... Okay, so maybe not all of the extras are quality.
All in all, this is a reasonable investment for self-respecting metal head, although anyone with less than two decades of existence will struggle to recognise a fair few of the participants. There is plenty of nostalgia here to provide an hearty evening's entertainment, but be warned - if you have any emotional investment in this genre of music, you will be found throwing your remote at the telly when that underground band who rocked your teenage socks off are nowhere to be seen on the DVD.