Daphne Blake

During the opening of a crime museum in Coolsville dedicated to the Mystery Inc. team, an attack by a reanimated Pterodactyl ghost is unleashed, orchestrated by the mysterious Masked Villain. The team fails to capture the ghost, and reporter Heather Jasper Hauff begins discrediting them in the media. Shaggy and Scooby feel guilty and decide to take things more seriously.

The team begins an investigation and suspects old enemies are behind the events. The trail leads to Jonathan Jacobo, previously presumed dead, and his former cellmate, Wickles. It turns out someone is using monster-animation technology, transforming stolen costumes into actual monsters using the substance "randomonium."

During their investigation, the heroes discover a laboratory where monsters are being created and suspect Patrick, the museum's caretaker. During the battle, they defeat all the monsters, turning them back into costumes. The villain turns out to be Heather Jasper Hauff, who is actually a mask hiding the living Jonathan Jacobo, who was bent on revenge against the team.

The heroes' reputations are restored, Velma begins a relationship with Patrick, and Scooby plays a video game based on the events in a post-credits scene. Your parents are away on vacation, so you stay at your cousin Daphne's house while they're gone.