This novel owes its vividness to being based on the author's own childhood experiences in a boarding school evacuated to a hunting lodge in the western Highlands of Scotland. On the seashore near the lodge was a standing stone. "This always gave me the shivers, though I had no idea why," Hughes said in a private interview. "I tried to exorcise this memory by writing a timetravel book set in Scotland and involving the stone." That manuscript was never published, and her need to "write out the stone" was still there.

Years later Hughes was looking through a dictionary of quotations for something else entirely, when the book fell open at a counting song she had never heard before: "The Seven Magpies." "A plot line, if ever I saw one," said Hughes. "Complete with the climax punch line: 'Seven for a secret that can ne'er be...