Many had expected The Silver Chair (book four) to follow The Voyage of the Dawn Treader. Author C.S. Lewis released Nephew as the sixth book in his seven-book series. According to The Guardian, the prequel is the second most popular book of the series.
Here’s more from the article: “The move would mean a return for [Jadis] the White Witch, played by Tilda Swinton in The Chronicles of Narnia: The Lion, the Witch and the Wardrobe, since Lewis’s later novel explains how she came to settle in Narnia. Even though her character was destroyed in the first film, The Magician’s Nephew goes back to a time before the first film and tells the story of how the White Witch originally came to Narnia. It is expected that Tilda Swinton will reprise the role.”