Scarlett Johansson and Oscar winner Lupita Nyong'o are in negotiations to join the voice cast of Warner Bros.' live-action/CGI hybrid The Jungle Book. The actress' join Idris Elba, who signed on back in March.This adaptation of Rudyard Kipling's beloved novel follows Mowgli, who has not been cast yet, a young boy who is raised in the wilderness by a pack of wolves, a bear and a black panther.