When Shaggy's rich Uncle Albert goes missing and is presumed dead, Shaggy receives an inheritance, which he uses to upgrade the Mystery Machine so it can transform itself into other types of vehicles. Before disappearing, Uncle Albert made some enemies and it is up to Shaggy and his trusty canine, Scooby-Doo, to defeat those enemies, the most dangerous of whom is evil Dr. Phineas Phibes. Armed with the upgraded Mystery Machine, a loyal robot servant and their new riches, Shaggy and Scooby must stop Dr. Phibes' evil plans and save the world.