Ned Flanders invites the Simpsons to a barbeque. When he announces that he is quitting his job to open a store that sells items to left-handed people. Homer hopes that the business will fail. Marge, meanwhile, worried that Bart is watching too much television and not getting enough exercise, allows him to take karate lessons in the mall. When Homer drops Bart off at his lesson, he visits Flanders's store, the Leftorium, and is pleased to see that Ned is doing poorly. At karate class, Bart discovers that he has to read books and work hard, so he goes to the arcade instead.

Ned's business flounders and he holds a yard sale to make ends meet. Homer buys Ned's best possessions for practically nothing. Although he runs into people who desperately need items especially made for lefties, Homer doesn't tell them about the Leftorium. Meanwhile, Bart continues to ditch karate class. He comes accross a gang of hoodlums trying to steal Lisa's saxaphone and Lisa calls upon him to use his karate skills to help her. Bart tries to fake his way out of the jam, but the thugs beat him up.

Homer's wish finally comes true: Flanders's business fails. Homer is guilt ridden when Ned loses his home and his family moves into their car. Only two days before Flanders is officially bankrupt, Homer calls his left-handed friends and tells them about Ned's unique store. As Ned's business starts to boom, the satisfied customers join in a chorus of "Put on a Happy Face."