Heavy metal begins not in America but in the industrial Black Country around Birmingham, where factory noise and steel-forging clangor seep into the music teenagers start making in the late 1960s. The film traces the sound back to Black Sabbath, formed by Tony Iommi and bandmates who grew up near the foundries and later channeled that clang into distorted, downtuned riffs. Archive performance footage and interviews follow the genre's early spread through Judas Priest and other Midlands bands, with musicians and critics describing how a working-class sound built on heavy machinery and grim postwar streets turned into a genre that would outlast the punk and prog movements around it. The documentary treats the music as a product of place as much as talent, tying specific songs and riffs back to the factories and terraced streets the bands grew up in. It closes with heavy metal's transformation from a regional curiosity into an internationally exported British genre.