The story revolves around a widowed father, Mr. Cedric Brown (played by Colin Firth), who struggles to manage his seven unruly and mischievous children: Simon, Tora, Lily, Eric, Sebastian, Christianna, and Aggie. The children’s behavior has scared away seventeen previous nannies, leaving Mr. Brown desperate for help.
In comes Nanny McPhee (played by Emma Thompson), a mysterious and magical nanny with a hideous appearance but extraordinary abilities. She arrives at the Brown household in response to Mr. Brown’s desperate plea for assistance.
Nanny McPhee employs unconventional methods to discipline the children, using her magical powers to teach them valuable life lessons about responsibility, kindness, and cooperation. With each lesson learned, Nanny McPhee’s appearance gradually transforms, becoming less frightening and more appealing.
Meanwhile, Mr. Brown faces financial difficulties and pressure from his wealthy Aunt Adelaide (played by Angela Lansbury), who threatens to separate him from his children if he doesn’t remarry within a month. Mr. Brown reluctantly agrees to consider marrying the obnoxious and snobbish Selma Quickly (played by Celia Imrie) to secure financial stability for his family.
As the children’s behavior improves under Nanny McPhee’s guidance, Mr. Brown begins to see the value of her unconventional methods and learns to appreciate her wisdom and compassion. However, when Selma Quickly’s true intentions are revealed, Mr. Brown realizes that he cannot sacrifice his family’s happiness for financial security.
In the climax of the film, Nanny McPhee’s work is complete, and she prepares to leave the Brown household. However, the children, now reformed and fond of their nanny, protest her departure. Before she leaves, Nanny McPhee reminds the children that they no longer need her because they have learned to behave and take care of each other.
As Nanny McPhee walks away, her appearance transforms into that of a beautiful woman, revealing her true identity as a magical being who comes to the aid of families in need. The film ends with the Brown family happily reunited and Nanny McPhee disappearing into the distance, ready to help another family in need.
Overall, “Nanny McPhee” is a heartwarming and whimsical tale about family, love, and the transformative power of kindness and understanding.