The iconic "Spinal Tap" are attempting to revive their career following a period of relative obscurity in America. They plan to promote their latest album and bring along a fictional fan, "Marty" (played by Rob Reiner), to create an intimate documentary showcasing the highs and lows—the good, the bad, and everything in between—of this band who represent both the positive and negative extremes of the music business, which the film satirizes with considerable amusement. Along with some well-executed musical performances that would have been right at home on MTV, we witness instances of greed and self-interest, some truly bizarre song lyrics, and a growing awareness that their days of playing massive stadium shows might be over. The arguments between band members never become genuinely nasty but disagreements about the censorship of their album cover by Walmart, their diminishing popularity now largely limited to college students, and their own failings provide an enjoyably realistic and often very humorous look at life as you decline in the entertainment world—and it’s quite critical of those who manage to earn a living through it despite lacking genuine ability but possessing unwavering self-confidence. This exemplifies British wit and irony presented within a mock reality that, even after forty years, continues to elicit frequent laughter.

Source on TMDB