In 1982 legendary British heavy metal band Spinal Tap attempt an American comeback tour accompanied by a fan who is also a film-maker. The resulting documentary, interspersed with powerful performances of Tap's pivotal music and profound lyrics, candidly follows a rock group heading towards crisis, culminating in the infamous affair of the eighteen-inch-high Stonehenge stage prop.

At 14, best friends Robb Reiner and Lips made a pact to rock together forever. Their band, Anvil, hailed as the "demi-gods of Canadian metal, " influenced a musical generation that includes Metallica, Slayer, and Anthrax, despite never hitting the big time. Following a calamitous European tour, Lips and Robb, now in their fifties, set off to record their 13th album in one last attempt to fulfill their boyhood dreams.