Keeping Mum is the story of Grace Hawkins (Maggie Smith) who is found guilty of murder as a young woman and sentenced to a mental institution for the criminally insane. As an older woman, Grace finds the opportunity to leave (escape) the institution and become a housekeeper for a family that is falling apart at the seams. Hired by the Reverend (Rowan Atkinson) and his wife (Kristin Scott Thomas), Grace soon endears herself to their family. Grace takes care of problems for everyone and teaches them how to relate and communicate with each other. At the same time, mysterious things happen, such as a barking dog disappears. Shortly, thereafter, the dog's owner seems to disappear as well. When the Reverends wife gets too close to an affair with her golf pro (Patrick Swayze), he too disappears. Yet the family is beginning to thrive and Grace is the epitomy of the perfect housekeeper.