A movie that isn't out yet has spawned a book that doesn't exist . . .
"Fireproof" is a movie set for release at the end of the month about a firefighter asked by his father to take a 40-day marriage challenge before divorcing his wife of seven years. The challenge involves reading and following an invented book THE LOVE DARE, "which eventually transforms him and his view of love, marriage, and faith." So test audiences for the movie asked how they could get the book--which didn't exist.
So two ministers in Georgia who had directed and produced the movie, "shut out the world and wrote for several weeks" to create a book "that helps readers learn each day about a unique aspect of the nature of love and offers a 'dare' to help implement that characteristic into their marriage." A publisher has apparently already sold 300,000 copies in advance of the movie's release.
This reminds me of Dorothy Gilman's book The Maze in the Heart of the Castle, which is a story about orphaned teen Colin who must find his way out of the maze. However, Gilman first described this story in her adult novel, The Tightrope Walker, a somewhat wistful standalone in which Amelia Jones begins her own journey of self discovery with references to Maze as being Amelia's favorite childhood story. Gilman must have fallen in love with her own description of Maze, so subsequently wrote it. I always wondered if anyone besides my sisters and me noticed this sequence of events. Gilman is certainly better known for her Mrs. Pollifax books but the others are very good too.