
The film discusses the traits and originators of some of metal's many subgenres, including the New Wave of British Heavy Metal, power metal, Nu metal, glam metal, thrash metal, black metal, and death metal. Dunn uses a family-tree-type flowchart to document some of the most popular metal subgenres. The film also explores various aspects of heavy metal culture.
Genres:

Sam Dunn as Self

Chris Adler as Self

Tom Araya as Self

Gavin Baddeley as Self

Blasphemer as Self

Randy Blythe as Self

Alice Cooper as Self

Pamela Des Barres as Self

Bruce Dickinson as Self

Ronnie James Dio as Self

Malcolm Dome as Self

George Fisher as Self

Tony Iommi as Self

Joey Jordison as Self

Lemmy Kilmister as Self

Kerry King as Self

Geddy Lee as Self

Tom Morello as Self

Jørn Stubberud as Self

Vince Neil as Self

Doro Pesch as Self

Dee Snider as Self

Corey Taylor as Self

Alex Webster as Self

Rob Zombie as Self

Fritz Hollings as Self (archive footage)
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