Velma wins first prize at her elementary school science fair with a computerized robot that Velma has programmed to do exactly what it's told. When mysterious locker robberies occur, Velma is the prime suspect. Things get even worse when her robot goes on a deadly rampage.

The gang accidentally gives Scooby the cold shoulder. Feeling they no longer need him, Scooby runs away. Realizing how cruel they were, the gang goes on a city-wide search for Scooby.

The Gang goes to the Coolsville amusement park. Shaggy and Scooby are excited because they will be the first ones to ride Monster Mountain - a giant roller coaster - for earning the most raffle tickets. Will they survive the emergence of a terrifying ghost clown?