"George [Lucas] and Steven [Spielberg] have been working on a script and it's almost there," a source explained. "Harrison [Ford] is on stand-by for filming next year. This looks like being an emotional and exciting conclusion to the franchise, with Indy facing his biggest challenge yet." The last film in the franchise, Indiana Jones and the Kingdom of the Crystal Skull, was released in 2008 and performed well at the box office, but was savaged by critics. Shia LaBeouf played Indiana's son Mutt Williams, and he will also appear in the new instalment. Movie bosses have assured fans the film will stay true to the series' roots, and won't contain lots of state-of-the-art special effects. "Shia LaBeouf has a central role again as Indy's son but this will be a blockbuster made in the old fashioned way rather than the CGI efforts of the last movie," the source added.