Sylvester Stallone became a worldwide phenomenon after starring in the Rambo film franchise. Deadline reports that Millennium Media is developing a prequel to the first film, Rambo: First Blood, and the film is being sold at Cannes. Titled John Rambo, the film will be directed by Sisu directorJalmari Helander from a script by Rory Haines and Sohrab Noshirvani (Black Adam). Principal photography is set to begin in Thailand in October. Details about the film are scarce, but it is expected to be an origin story about Young John Rambo during the Vietnam War. It is being reported that Stallone is aware of the project, but he's not involved. However, its producers have left the door open should a fitting role arise. Casting is in the early stages.