Lisa embarks on a career as a babysitter. She starts by watching Rod and Todd Flanders, which leads to numerous other babysitting gigs all over Springfield. When Homer and Marge decide they need some time to be alone together, they put Lisa in charge of Maggie and Bart. Bart is furious that his little sister is his babysitter and rebels as much as possible. Lisa tries to deal with Bart's numerous pranks and distractions, but things go a little too far and Lisa accidentally dislocates Bart's arm by pushing him down the stairs. Intent on getting Lisa in trouble, Bart hurts himself even more, knocking himself out. Panicked, Lisa tries to cover up what happened but winds up turning her failure as a babysitter into a public spectacle. At first, Lisa is sure no parents will ever trust her with their kids again, but sure enough, her clients call again and her business continues.