Katie is dreading the boring summer ahead, while her best friends are all away at camp. But when Katie gets a job catsitting for her upstairs neighbor, things get interesting. First, Madeline has 217 cats. And they're not exactly... normal cats. Plus, Madeline only seems to go out exactly when the Mousetress, the city's most notorious villain, commits crimes?! Could it be that Katie's neighbor is really a super villain? Can Katie wrangle a whole lot of wayward cats, save a best friendship, and crack the biggest story in the city's history?
