Scooby-doo

                                                  Plot...

              In a warehouse, the Mystery, Inc. gang illustrates a plan to catch the Luna Ghost who has kidnapped Daphne Blake (Sarah Michelle Gellar), flying around with her bound and gagged which goes astray but ends with Shaggy Rogers, (Matthew Lillard) and Scooby-Doo, (Neil Fanning) causing the Ghost to be caught. After solving the mystery, constant arguments among the members of Mystery Incorporated about Fred Jones (Freddie Prinze, Jr.) taking credit for Velma Dinkley's (Linda Cardellini) ideas cause the gang to go their separate ways, much to the sadness of Shaggy and Scooby. Two years later, Shaggy and Scooby are approached to solve the mystery of the popular horror resort Spooky Island, reuniting with Fred, Daphne and Velma, although none of the latter are thrilled to see each other, except for Shaggy and Scooby, who still want Mystery Incorporated to re-unite. On the island, the gang meets Emile Mondavarious (Rowan Atkinson), the park's owner, who explains his theory that visitors are being cursed. Shaggy falls in love with a girl named Mary Jane (Isla Fisher), while Scooby is mysteriously targeted by demonic creatures. Velma meets a man named N'Goo Tuana and his henchman, the famous luchador Zarkos, who explains that demons once ruled the island.
The gang visits the island's abandoned ghost castle, where Daphne finds a pyramid-shaped artifact called the Daemon Ritus and Velma and Fred find a strange room with videos designed to address non-humans. When the gang returns to the hotel, they are attacked by the island demons, who kidnap numerous tourists including Fred, Velma and Mondavarious. The next day, Daphne is captured by Zarkos, while Shaggy and Scooby discover Fred, Velma and the tourists are now possessed by the demons. The two flee with Mary Jane, until Scooby realizes she is possessed as well. In the midst of an argument between Scooby and Shaggy, Scooby falls down a hole, followed by Shaggy, who dives in to save him. Shaggy comes across a vat containing the protoplasmic souls of everyone who was captured, including the rest of the gang, and releases the gangs' souls to their bodies. Velma discovers that the demons are destroyed in sunlight just like vampires, while Daphne and Fred's souls end up in the wrong bodies.
Shaggy steals the Daemon Ritus and reunites with the gang after their souls correct themselves. Coming across Voodoo Maestro, the gang learns that if the leader of the demons absorbs a pure soul through the Daemon Ritus, then the demons shall rule the world for the next 10,000 years. The pure soul belongs to Scooby, while the demons' leader is Mondavarious. Shaggy convinces the gang to put their differences aside and finally work together to save Scooby. They form a plan but it fails and Scooby's soul is extracted. Scooby is saved by Shaggy, wounding Mondavarious in the attempt. Fred and Velma discover he is actually a robot, controlled by none other than Scooby's nephew, Scrappy-Doo (Scott Innes), who the gang abandoned years ago due to his egotism. Now vengeful, Scrappy transforms into a giant demon called Scrappy Rex (J. P. Manoux)

to destroy the gang and rule the world using the tourists' souls he absorbed.
Daphne fights Zarkos above the island's caves, knocking him through the roof, which exposes the demons to sunlight and kills them. Shaggy confronts Scrappy and rips the Daemon Ritus from his chest, freeing the souls and reverting Scrappy to his original self. Shaggy finds the real Mondavarious trapped in a hole and frees him. Scrappy and his minions are arrested. Daphne and Fred kiss, Shaggy and Mary-Jane hug along with Scooby, and Velma hugs a man she met earlier then punched him while laughing. When Mystery Incorporated addresses the press, Velma thinks that Fred will take credit for her ideas again, however Fred lets Velma take the credit she deserves after feeling bad for her. Mystery Incorporated is then re-united after Scrappy-Doo and Zarkos are arrested.
At the end, Scooby and Shaggy are eating food at the Spooky Island hotel. They both eat hot peppers and scream as smoke comes out of the hotel.