Claudia isn't worried when she hears her newest baby-sitting charge, Betsy Sobak, is a big practical joker. After all, how much harm can one little girl do? Plenty! Claudia breaks her leg as a result of one of Betsy's jokes. Now Claudia is feeling like baby-sitting might be too dangerous and she's talking about quitting the club. Kristy thinks Betsy needs to be taught a lesson, and that the baby-sitters are just the ones to do it. Watch out, Betsy Sobak. The joke war is on!