Decades after her original visit, the magical nanny returns to help Michael's three children, along with grown-up Jane and Michael Banks, through a difficult period in their lives.

Mrs. Merkle mysteriously appears as widower Seth Webster is looking for a nanny and housekeeper to help with his twin boys, and she quickly becomes irreplaceable as an employee, friend, and matchmaker. When her acting career does not take off, but her sister does with her fiance, Reba returns home to become a preschool teacher, and director of the Christmas pageant. After his wife dies, widower Seth Webster moves to town with his rambunctious twin...

Nanny McPhee can tame even the most unruly children with a tap of her magic walking stick. Her latest challenge is the bratty brood of a recent widower Mr. Brown. He is under pressure to find a new wife or lose his much-needed allowance from wealthy Aunt Adelaide. His love for scullery maid Evangeline remains unspoken as he wincingly woos the eagerly merry widow Mrs. Quickly, but Brown's raucous rugrats have a plan to make things right, especially...