In her mid-eighties, retired school teacher, Matilda Thistlethwaite lives each day to the fullest. Keeping her body in fine fettle with yoga exercises, church and community activities, and good-hearted meddling, Tillie, as she is known to her many friends, works to keep her mind sharp with a regimen of "cerebral calisthenics", a seemingly endless series of self-improvement classes. However, whether leading a senior citizens' yoga class, baking boxes...