Nanny McPhee appears at the doorway of a young mother, Mrs. Isabel Green, who is trying to perform on the family farm while her husband is away at war. But once she's arrived, Nanny McPhee finds that the kiddies are fighting a war with their own. Relying from a flying bicycle along with a statue that comes into a baby elephant and a piglet, Nanny uses her magical to show her mischievous charges five lessons.