Upon arrival, they learn that the opera house in which the show will be held is being terrorized by a Phantom, who is intensely lauding one of the finalists to win, Chrissy, a spoiled girl whose noisy parents are no more polite than she is.

During the dress rehearsal, the Phantom sabotages most of the finalists’ acts, leaving Chrissy, Emma, and Fred and Daphne as the only contestants left.

With the help of Steve, they catch the Phantom, who is revealed to be Mel Richmond, hoping to collect the insurance money on the opera house.

However, Shaggy and Scooby find out that assistant director Dewey Ottoman is also a Phantom, when they see him putting on lemon-scented hand sanitizer.

Ottoman is arrested and the gang return to the opera house just in time for Fred and Daphne to participate in a tie-breaker performance.

During the credits, the gang stops at a gas station where they see the news that Steve has become the new host of Talent Star after the show has been renewed for a tenth season.

DVD Verdict offered that the plot was an unoriginal "rip-off of the classic The Phantom of the Opera" mixed with "overtones of American Idol" as well as other "reality based music shows".

Fox, Peter MacNicol, and Wayne Brady in supporting roles "make the film slightly more interesting for adults who want to play the 'is that so-and-so's voice?'