Mark has just moved to suburban Arizona and has trouble reconciling life there with the life he knew in the Big Apple where he grew up. His father has landed a job with the school board and has forgotten what it was like to be a kid. Mark's alienation manifests itself in a radio show he starts with a short wave radio his father got him so he could talk to his friends back home. He couldn't reach anyone and so Happy Harry Hard-On was born.

Needless to say, Mark strikes a chord with the discarded youth at his school and becomes something of spokesperson for their frustrations. As the movie unfolds and Happy Harry becomes more of an influence on the teens, the administration of the school becomes less and less able to deal with the flood of discord, rebellion and individuality the students begin to show. In the end, the administration is revealed as corrupt and is overthrown.

Towards the climax of the film, Mark becomes unable to deal with the overwhelming response to his late night ramblings, and tries to disingage himself. The more Mark tries to distance himself from what he has unleashed, the more his actions become misterpreted and actually dangerous, a far cry from the playful late night radio show he started. When Mark's ingenuity outwits first the administration of the school, then the local police, and finally the government, the overwhelming sense that it is only a matter of time before he is caught can lend itself to many Christian interpretations. Although these are apparent, there is a simpler and more important message that eventually comes through.

Mark becomes a symbol, a messiah of sorts for the youth of America, in the end telling them to shout out their own individuality and start their own radio stations, since he is inside each and every one of them. The somewhat upbeat ending is only emphasised by the fact that ten years later there is very little actual difference in the structure of suburban life, and that although this film was one of, if not the first, in a long line of disenfranchised suburban youth movies, a lot of good has come out of the pop-up housing and 'teenage wastelands'. The growth of independent musicians and the 'indie rock' scene, filmmakers such as Kevin Smith and Richard Linklatter (of Slackers), even movies and TV shows like the Scream series and Buffy the Vampire Slayer add a new twist to suburban life. In the end the message of Pump up the Volume is clear: we don't need the stimulus of high art and culture to make us great and capable of great things. We all have the capacity to be great on our own, on our own terms.