Based upon the true story of London playwright and actor Alan Bennett's (Alex Jennings') unusual multi-year relationship with an eccentric elderly, homeless woman he knew as Miss Mary Shepherd (Dame Maggie Smith) in the 1970s before allowing her to park her van in the driveway of his home. She stayed there for fifteen years. Miss Shepherd was, in fact, Margaret Fairchild, former pupil of pianist Alfred Cortot. She played Chopin in a concert, and after she tried to become a nun, was institutionalized by her brother. Living in fear of being caught and sent back, she had an accident when her van was hit by a motorcyclist for which she believed herself to blame, and thereafter was also fearful of arrest.