Amidst a screening for the film's trailer, Mr. Hyde, a villain from the Blue Falcon television series, emerges to terrorize the conventioneers.

Having been humiliated during the attack, San De Pedro's mayor, Ron Starlin, fires Mystery Inc. and has their access to the convention revoked.

Seeing Austin in danger, the duo rescue him before their friends arrive to defeat the giant Hyde and discover that it was actually a mech seemingly piloted by Garrison.

After forcing the premiere to be held at the stadium and planting Garrison in the mech, he used the attack to divert the armored car into a detour so he could make off with the five million dollars worth of the convention's entrance fees it had.

Sometime later, an impressed Severin produces a sequel to her Blue Falcon film, with Garrison guest starring as the father of Adams' character and Scooby as Dynomutt.