1982 and the worlds loudest rock band, Spinal Tap, are about to embark on their biggest world tour to date. Along for the ride is film-maker and fan Marti DiBergi (Rob Reiner), there to make a behind-the-scenes tribute to his favourite heavy metal band. However instead of a celebrating the genius of the musicians behind such classics as Big Bottom and Hell Hole, the documentary captures the cracks as they begin to appear for this band whose time has come and now appears to have gone again. Whilst the tour turns out to be not the sell-out they had hoped for, the bands hapless manager Ian Faith (Tony Hendra) unwittingly orchestrates a cacophony of errors: stage props malfunctions, miniature sets and an all-black album cover to replace one that the record company deemed too offensive to women: Whats wrong with being sexy? The final straw however might just prove to be the interference of guitarist David St. Hubbinss girlfriend Janine in the bands business affairs, shutting out childhood friend and co-lead guitarist Nigel Tufnel. With a camera recording all the chaos, the archetypal portrait of a band in crisis is born.