Don Adams, head of the Adams Exterminator Company, "Bug Killer To The Stars," guest stars with Scooby and the gang. The comedy unfolds when Scooby and the kids stop on Sunset Boulevard to help troubled motorist Adams. But the engine is infested with some vengeful, metal-munching termites that completely devour the motor. Scooby and the kids volunteer to help him with his next job. High on the mysterious Horror Hill sits the eerie, foreboding home of former horror-film star, Lorne Chumley. Scooby and the kids momentarily hesitate to enter when Adams reveals that fourteen exterminators had been sent there before--and no one has heard from any of them since. At the door, they are met by Otto, the sinister butler, who informs Adams that Mr. Chumley does not require his exterminating services. But Adams insists, telling Otto that the bank is foreclosing on the house and he must eradicate any bugs before it can be sold.

Cass Elliot, former singer with The Mamas and the Papas, hires Scooby-Doo and the Mystery, Inc. kids to investigate two living globs of green cotton candy creating a sticky mess at her Sugarplum Candy Company.