"This Is Spinal Tap" shines a light on the self-contained universe of a metal band struggling to get back on the charts, including everything from its complicated history of ups and downs, gold albums, name changes and undersold concert dates, along with the full host of requisite groupies, promoters, hangers-on and historians, sessions, release events and those special behind-the-scenes moments that keep it all real.

The now estranged bandmates of Spinal Tap are forced to reunite for one final concert, hoping it will solidify their place in the pantheon of rock 'n' roll.