Based on the "Nurse Matilda" books by Christianna Brand comes the story of Nanny McPhee. Cedric Brown (Colin Firth) is now a widow with seven ill-behaved children who've already chased away 17 nannies. But when a mysterious voice tells Cedric to hire Nanny McPhee (Emma Thompson), she arrives at the Brown home and the kids learn to behave properly. But when Great-Aunt Adelaide (Angela Lansbury) tells Cedric he must be married by the end of the month or she'll separate the children, he tries to find women, but the children run them away. And Nanny McPhee tells Simon (Thomas Sangster), the eldest, that he will face the consequences, so the kids go to Selma Quickly (Celia Imrie) and admit what they did and ask to give their father a second chance and they will be married. Will the kids really find the perfect woman for their father?