Mr. Hyde, alias Willie The Weasel, abetted by Hyde Dog, demands to be mayor of Big City, threatening its citizens with a sinister formula that turns them into evil Hyde-like creatures. Blue Falcon and Dog Wonder, assisted by the Scooby-Doo detectives, plan to trap the wily Mr. Hyde and agree to his request. Once this results, Mr. Hyde, via his terrible greed, is snared into a wild falcon fracus: Dynomutt captures Hyde Dog and the antidote that will save Big City, with Blue Falcon's Falconclaw scooping up the fleeing Willie The Weasel, b.k.a. Mr. Hyde. After being commended by the Mayor, Dynomutt, executing a heroic exit from City Hall, accidentally gets caught in one of Shaggy's Scooby-traps!

Dog Wonder and B.F., teamed with the Scooby-Doo crimestoppers, meet Lowbrow, a villain desiring to be king of crime employing the knowledge from the books of Big City University to further his dastardly schemes. This primitive thief unwittingly leads Blue Falcon, Dynomutt and Scooby Doo and company to his lair, where they discover his latest plan: robbery of Big City Mint! Blue Falcon and Dynomutt set a trap for Lowbrow and thwart his evil plans, using an ""Instant Delayed Action Falcon Balloon,"" which captures him and neatly deposits him into prison. Later, at a restaurant, Blue Falcon and Dynomutt treat Scooby and friends to a turkey dinner, for their help in apprehending Lowbrow. Dyno volunteers to carve the turkey, but, instead of a Dyno-carving Knife, his paws malfunctioningly turn into Dyno-Mallets, which pound the poor turkey mercilessly flat. (""Anybody for turkey pancake?"")