Watch Scooby Doo! The Mystery Begins

The film begins in Coolsville, Ohio, as four teens are roped into a fight inside of a school bus and summarily sent to detention. These four kids; Norville Rogers, aka Shaggy, is a nerd who tried to sneak his dog Scooby-Doo on board, Fred Jones is a football team quarterback, Velma Dinkley is a science whiz, and Daphne Blake is in Drama; form a bond over their common curiosity regarding mysteries, but swiftly agitate each other. While the teens are sequestered in the library to serve detention, two ghosts manifest and chase the kids into the gym where a pep rally is being held. A third ghost, known as The Specter, appears and tells everyone to leave the school. Principle Deedle closes the school, however Vice Principal Grimes considers the mess to be an elaborate prank and suspends the kids. The teens try to clear their names through investigating the ghosts, earning Grimes' ire even further and getting them expelled. Undaunted, the kids investigate the school in a disguise, learning that Grimes is the prime suspect. They decide to sneak into Grimes' house at night, where all four black out. The Specter is present when the kids awaken and, while keeping Scooby and Grimes as collateral, forces the teens to look underground for a time capsule. This turns out to be a fool's errand, but the kids manage to trick the Specter into helping them get the capsule out of a hole. However, the plan is botched as they lock him in a flooded room--the very resting place of the time capsule. The gang manages to reacquire the time capsule and uses a spellbook to exorcise the ghosts. Scooby breaks free in time to restrain the Specter, revealed to be the head principal. Deedle explains that a valuable stamp misprint was within the time capsule. As Deedle is sent to prison, the gang is commended and readmitted by Grimes, and they continue to investigate mysteries.