Emma tries to help her parents understand that, although their beloved new nanny has made a few mistakes, no one can behave perfectly responsibly all the time.

When Milton Worthy learns his classroom's pet ferret is the evil mastermind behind a dastardly plot for world domination, it's more than just about any kid could handle. But then not every kid is the son of a member of the super-secret, super-awesome Society of Substitutes! Now it's up to Milton and his substitute teacher mom to save Beacher Elementary School before time runs out.