Scooby-Doo, an unnatural dog that can talk finds himself lost in Coolsville. Shaggy Rogers finds him and brings him home. The two bond and Shaggy sneaks him into high school. They are sent to detention after accidentally messing up the library along with Fred Jones, Daphne Blake, and Velma Dinkley. While in detention the 5 encounter a ghost, haunting the school.
The 5 team up and name themselves the mystery gang. They try to solve what the ghost is, is it the supernatural or just a man in a mask? The group of teens will grow to be much more than friends.
