Valancy Stirling is twenty-nine, unmarried (and thus considered an "old maid"), and has lived her entire life with her nagging mother and gossip-minded extended family who actively discourage happiness and treat Valancy like a child. She retreats from her unhappy circumstances with flights of imaginative fantasy, centring on daydreams of her imaginary "Blue Castle," and finding refuge in the books of her favourite author, John Foster, who writes about the great beauty of nature. When Valancy is diagnosed with a terminal heart ailment, she hides it from her family and, at the same time, realizes she has never been happy in her life, so she rebels against the colourless life that her family has always imposed on her.
