A year after Bowser's attempt to marry the Princess was thwarted, Seven of his children take over his throne and begin a new fleet of villains. Unknowingly, Morton (the oldest) hires two human brothers and rival plumbers Wario and Waluigi, to spy on Mario and Luigi. Speaking of which, the two trusty plumbers find a lost creature in their apartment, which they name Yoshi. Together with Peach and Toad, they must defeat the koopalings, and return Yoshi with a help of an unknown princess.
