The Mystery Inc. gang has been invited to compete in the annual Teen Mystery Solvers Convention A weekend affair where mystery-solving teams from around the country compete to solve a mystery. But when the mystery turns out to be the disappearance of the teams themselves, it is up to the team sidekicks -- led by Scooby-Doo -- to find out whats behind it all. And this mystery needs to be solved by the end of the weekend. or theyll never see their friends again.