Katie is dreading the boring summer ahead while her best friends are all away at camp—something that’s way out her mum’s budget, unless Katie can figure out a way to earn the money herself. But when Katie gets a job catsitting for her mysterious upstairs neighbour, life gets interesting. First, Madeline has 217 cats (!) and they’re not exactly ... normal cats. Also, why is Madeline always out exactly when a notorious villain commits crimes?! Is Katie’s upstairs neighbour really a super villain?