open with the age old question of what be the first heavy metal song before launch into a metal head history of the genre this fascinating documentary be a must . with interview from rock great like lemmy and tomy iommi and alice cooper and vince neil to name but a few and concert footage of various heavy band from black sabbath to slipknot this be a sweaty and mosh pit induce and bleed ear look at what heavy metal music be and mean to thousand of fan the world over . it be well make and surprisingly funny and brilliantly pace . there be moment in the film when the hair on my neck stand up a memory be evoke by what i be watch . see rage against the machine perform kill in the name of and all the fan sing along remind me of when i saw them fourteen year ago in room with no more than a hundred people . you can not beat the feeling of see a massive rock concert and the film manage to capture that feel with the sight and sound it be almost like you can smell the sweat . the maker also do not shy away from the controversy that have be level at the music over the year and delve into the various court case and why so many believe it the devil music . overall it be a thoroughly engage look at heavy metal and all that encompass and make by a fan for fan but open to anyone and be you ready to rock .