The story of the longest surviving and certainly the loudest genre of rock, heavy metal. With no sign of disappearing, metal has been the most controversial and misunderstood of all rock genres. With Black Sabbath as the undisputed Godfathers, we follow their highs and lows, and, along the journey, meet Deep Purple, Judas Priest, Iron Maiden and Metallica.

The film documents the English heavy metal band Black Sabbath's final show of their farewell concert tour, The End Tour. The performance was held at the Genting Arena in Birmingham, England, hometown of the band's founding members: vocalist Ozzy Osbourne, guitarist Tony Iommi, bassist Geezer Butler, and drummer Bill Ward. Osbourne, Iommi, and Butler performed this final concert with session drummer Tommy Clufetos in place of Ward, as well as Adam Wakeman on keyboards and guitar.
The concert opens with a performance of the song 'Black Sabbath'. The film goes on to show the band performing 'Fairies Wear Boots', 'Under the Sun/Every Day Comes and Goes', 'Into the Void', 'Snowblind', 'War Pigs', 'Hand of Doom', 'Iron Man', and 'Children of the Grave'; at the end of the setlist, the band performs the song 'Paranoid' as an encore.
Interspersed with the final concert are interviews with Osbourne, Iommi, and Butler, in which they talk about their careers and past drug addictions. Additionally, Iommi's 2012 lymphoma diagnosis, which impacted the band's 2012–14 reunion tour and the recording of their 2013 album 13, is discussed. The film also features footage of 'The Angelic Sessions'—the band's final studio recordings, which took place in the days following the final show. Of these recordings, the film shows Osbourne, Iommi, and Butler performing 'The Wizard', 'Wicked World', and 'Changes'.