When Lenny wins the lottery and invites the Simpson family to a celebratory party at a posh hotel, Bart meets his doppelganger, Simon Woosterfield, who happens to be a member of the richest family in Springfield. Simon and Bart decide to switch places, and Bart arrives at the lavish Woosterfield mansion only to find football great Joe Montana (guest-voicing as himself) hanging around the estate. As Simon adjusts to the simple life over at the Simpson household, Bart begins to notice his wealthy new siblings acting strangely toward him. With some frightening words of wisdom from Mr. Burns, Bart realizes his new siblings are plotting his demise so they can inherit the Woosterfield family fortune all for themselves. Lisa and Simon must reach Bart before he goes from riches to ditches.