Swamp Rat and his henchman Mudmouth plan to flood Big City by using stolen pumps to send half the water in Bogmyer Swamp into Big City to start a crime spree. Blue Falcon and Dynomutt, team-up once again with Scooby-Doo and Mystery Inc. to stop the villains before Big City becomes Bog City. NOTE: This episode is another crossover between Dynomutt, Dog Wonder and Scooby-Doo.