Apparently, the rights to make a film out of the book were bought by Walden Media way back in 2006 around the same time they were working on The Chronicles of Narnia: The Lion The Witch, and the Wardrobe. According to Variety way back in 2007, it was supposed to be produced by Ralph Winter (X-Men, Fantastic Four), Randy Argue and Lewis' stepson Douglas Gresham. Winter stated at that time that the movie would be "With the right script...dealing with temptation and that whole upside down world, it could be a very, very interesting movie. And it's going to be dark. This isn't a light, happy, Narnia piece."
So what happened? Where did the movie go? Was it shelved when Prince Caspian didn't deliver the way everyone hoped it would after the success of the first Narnia movie? I would totally believe that. I would also believe that they can't figure out how to translate the book into a movie. As I read it, I don't see how they could script something like that.
