In Coolsville, Ohio, a pet adoption fair is held. Scooby-Doo is up for adoption, but nobody wants him. Later, on the way back to the pound, Scooby is accidentally left behind. Seeking shelter from a thunderstorm, he comes across a graveyard where he witnesses two ghosts rise from their graves. Scooby panics and runs away, ending up in the bedroom of Norville "Shaggy" Rogers, a clumsy and geeky outcast. The two quickly bond and Shaggy adopts Scooby. Later, Shaggy tries to smuggle Scooby onto the school bus, but a fight breaks out which causes the bus to crash into a flagpole, which falls on Vice Principal Grimes' car, smashing its windshield. Because of the fight on the bus and the damage to Grimes' car, Shaggy is sent to the library for detention, along with three others: Fred Jones, the quarterback of the football team; Velma Dinkley, a science nerd; and Daphne Blake, a wealthy drama club student. They bond somewhat over a shared interest in mysteries, but quickly get on each other's nerves. Two ghosts suddenly appear and chase them to the gym where a pep rally is taking place. A third ghost, The Specter appears, causing the lights in the building to flicker. He starts telling everyone to leave. The stamp-collecting Principal Deedle decides to close the school, but Vice Principal Grimes deems it a prank and suspends the quartet as he refuses to believe that there are ghosts in the school. The gang tries to clear their names by investigating the ghosts at the school, which leads to Grimes expelling them and threatening to have them arrested if they're caught sneaking into the school again after Grimes still refuses to believe that the ghosts are at the school. Further investigation, in disguise at the school, makes them think Grimes is their prime suspect. Searching at night at Grimes' house leads them to information about a time capsule. The ghosts attack again, and the teens are knocked out. The Specter, keeping Scooby and Grimes as prisoners, forces the gang to search underground for the time capsule. Unable to find the capsule, they trick the Specter into coming down to carry the capsule out of the hole, but the plan backfires when they try to lock him up in a flooded room, and the Specter acquires the capsule. Stealing the capsule back, the gang uses a book of spells to banish the ghosts. Scooby manages to break free of his restraints and arrives just in time to subdue the Specter, who turns out to be Principal Deedle. The principal reveals that a stamp misprint was hidden within the time capsule, something that would have been worth a fortune. The time capsule was meant to be buried when the school first opened, but a flood hit the town that day and the capsule was lost in the old school underneath the new school. Deedle, being determined to claim the misprint in the time capsule, used the spell book to summon the ghosts to scare everyone away so he as the Specter can open the time capsule himself. As the exposed Deedle is fired from his job and sent to prison for his crimes, the group is re-enrolled into Coolsville High publicly congratulated by Grimes, who becomes the new Principal. Grimes also apologises to the gang for falsely accusing them. Grimes then announces they’re officially going to bury the Coolsville Academy time capsule. The gang begins digging, but in the process, Shaggy accidentally throws his shovel, which falls on Grimes’ car, once again smashing its windshield. Instead of giving him a detention, Grimes forgives Shaggy. In the film's ending, the group decide to stay together and solve mysteries, and they head off to "investigate some strange goings-on at the Coolsville museum", a hint to the very first episode of Scooby-Doo, Where Are You! and their very first villain, the Black Knight Ghost.
Filming took place in Vancouver, British Columbia, Canada, including Templeton Secondary School from August 4, 2008. Cartoon Network's content advisor Rob Sorcher had said, "This contemporary take on Scooby-Doo will be an exciting movie event on Cartoon Network. This project is also an anchor component of our new push into movies, our great partnership with Warner Premiere and the overall expectation of Cartoon Network programming efforts." The trailer for Scooby-Doo! The Mystery Begins was first seen on the DVD of Scooby-Doo! and the Samurai Sword, 17 Again and Shorts.
Reception
Scooby-Doo! The Mystery Begins was the most-watched telecast in Cartoon Network history with 6.1 million viewers on September 13, 2009, outdistancing the previous high of 3.9 million viewers that tuned into the premiere of the animated series . The film received largely positive reviews in Variety and Los Angeles Times.
Sequel
Due to the success of Scooby-Doo! The Mystery Begins, a sequel went into development in October 2009. Titled Scooby-Doo! Curse of the Lake Monster, principal photography commenced on March 15, 2010 in various locations around Southern California. The sequel aired on October 16, 2010 and was released on DVD in 2011.
