Valancy, living with her mother and her cousin, is a confirmed old maid at the age of twenty-nine, miserable at how she is squelched and belittled by all her family -- including all the extended relatives. But on her birthday, she gets up her gumption and goes to visit the local doctor about the heart pains she feels.
The doctor is called off abruptly because his only son was in an accident, but she gets a letter with her diagnosis. The heart problem is fatal and will kill her within a year at the latest. And Valancy realizes she's never been happy, and she has nothing to fear, because she will not be a scorned old maid for much longer.
It starts with her telling everyone what she actually thinks at a family dinner party. It does not end there. Her adventures have her living in two additional places during the course of the year, much to the horror of her family, who realize that everyone will know how insanely she's acting. She doesn't care much that she's disowned. And she sees much of the wilds about her home before the year draws to a close -- and new discoveries are made.