Scooby-Doo and the rest of the ghost-busting gang visit a quiet farm town where everyone is preparing for the annual Halloween harvest celebration.

Fievel and his friend Tony Toponi find a map that they believe points to a treasure buried somewhere beneath Old New York, and the plucky rodent is determined to find it. However, what he discovers under the city is a tribe of Native American mice who were driven underground by prejudiced European immigrants.