In the first version of the fantasy book The Hobbit, the creature Gollum helps the hero, Bilbo, leave a cave after a riddle game.
While writing the next book, The Lord of the Rings, author J.R.R. Tolkien made Bilbo’s magic ring more dangerous. He changed the earlier scene: Gollum chases Bilbo, who turns invisible to escape.
The new chapter appeared in 1951. The later story had changed the earlier book.