The gang head to Dooville to see Scooby's family, and arrive just in time to attend Professor Phantasmo's Circus Fantastique, where everything is free. Soon Scooby and Shaggy come to realize that the calliope music that plays in the circus is hypnotizing everyone into not noticing that it's a "circus of living evil." Flim Flam, however, becomes entranced by the allure of the circus, and decides to become Phantasmo's business partner. Further complications ensue when Bogel and Weerd begin meddling in matters.