Esme Pearl has a babysitters club. It's kinda lame, but Esme likes babysitting, and she's good at it. And she needs the money-- it seems like destruction follows her wherever she goes. Why is Cassandra Heaven willing to do anything, even take on a potty-training two-year-old, to join Esme's babysitters club? Turns out, Esme and Cassandra have a lot in common, and they're about to discover what being a babysitter really means: a heroic lineage of superpowers, magic rituals, and saving the innocent from seriously terrifying evil. And all before the parents get home.