Broad satire and buffoonery presented as a series of movie trailers. Among the titles and subjects are: "The Howard Huge Story", "Skate-boarders from Hell", "The Invasion of the Penis Snatchers", Woody Allen (pre-Mia), movie trailer come-ons, Charlie Chaplin, war movies, Billy Jack. The source of the title is presented about an hour into the film.

Although Jo Jo Dancer has achieved success as a stand-up comedian, he hasn't found happiness. After receiving severe burns in a narcotics-related incident, Jo Jo remains in a coma, and, while in this state, he looks back on his life. Drifting off into memories of his troubled childhood, Jo Jo revisits his youth, recalling his eventual rise to fame and the decadence that followed. As he considers his existence, he must decide if he wants to go on living or not.

A young girl is accidentally run down by a car driven by a careless city slicker. This careless injustice provokes the girl's grandfather into summoning his mystical powers and placing a death curse on the young man. Desperate to stave off the dire consequences of the hex, Barry seeks the counsel of a local psychic medium

"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.