“What was she doing in Mexico?” asks Hermione Lee in her biography of Penelope Fitzgerald. 1 In October 1952, decades before Fitzgerald became one of the most celebrated British novelists of the twentieth century, she and her five-year-old son, Valpy, sailed from England to New York City and took a bus south of the border, where they remained until January 1953. Fitzgerald’s husband, Desmond, and their two-year-old daughter, Tina, stayed behind. Fitzgerald was pregnant with their third child, Maria, who was born a couple of months after she and Valpy returned.

In a 1980 essay called “Following the Plot,” Fitzgerald briefly describes her time in Mexico, which she says she wanted to use as the basis for a novel. The voyage, she writes, was proposed by “two old ladies called Delaney” from a Mexican city named Fonseca. The women

lived comfortably, in spite of recent economic reforms, on the proceeds of the family silver mine….…