Nanny McPhee arrives to help a harried young mother who is trying to run the family farm while her husband is away at war, though she uses her magic to teach the woman's children and their two spoiled cousins five new lessons.

Nanny McPhee: I hear you've been naughty.
Celia: Where are we?
Cyril: We are in the land of poo. Duck poo, cow poo, goat poo.
Nanny McPhee: Leave it to me.
Mrs. Docherty: You seem to have forgotten the way she works. When you need her but do not want her, then she must stay. When you want her, but no longer need her, then she has to go. I know from personal experience.
Nanny McPhee: These children need me.
Nanny McPhee: I am Nanny McPhee. Small C, Big P.
Megsie: Nanny McPhee we need you!