Mila Kunis and James Franco have officially joined Walt Disney Pictures: Oz, the Great and Powerful. Variety report that the pair have been cast, Kunis will play "Theodora" a witch who will eventually become the Wicked Witch of the West, as the youngest sister of "Evanora" [the Wicked Witch of the East in the original Oz stories and film] and Franco will play the Wizard. Sam Raimi will helm the prequel to the 1939 The Wizard of Oz. The story of Oz: The Great and Powerful, follows the future wizard, a circus wrangler in the real world, as he is carried away to the magical land by a tornado.