The Blue Castle - Lucy Maud Montgomery

Valancy Stirling, plain, twenty nine, and as yet unsought, is given a year to live by a great heart specialist. This is the story of her year in which she finds a blue castle of happiness in the Canadian woods.

The Blue Castle is a 1926 novel by Canadian author Lucy Maud Montgomery, best known for her novel Anne of Green Gables. (Summary adapted from ALA Booklist)