When Bean's parents leave her older sister Nancy in charge for the afternoon, Bean knows she is in for a tough time. Nancy is acting far too bossy, so Bean decides to prove that her big sister is actually the worst babysitter in the entire world. But she cannot do it alone. She calls on her best friend, Ivy, to come over and help with a top-secret mission to teach Nancy a lesson. Ivy and Bean hatch a brilliant plan to show Nancy exactly what it takes to be a good babysitter. But as with all of their big ideas, things do not go exactly the way they hoped. The afternoon quickly spins into a whirlwind of unexpected surprises, hilarious mistakes, and laugh-out-loud moments. Jump into another adventure with the neighborhood's favorite duo as they try to outsmart their babysitter. It is a story packed with big imagination, tricky schemes, and the very best kind of friendship.