This was on Dark Horizons website about Rambo 4 or its offical title of John Rambo:
"Lionsgate will release Sylvester Stallone's "John Rambo" on January 25th 2008.
Set in Thailand, the story follows a group of Christian aid workers who recruit John Rambo (Sylvester Stallone) to guide them up the Salween River to deliver medical supplies to the Karen tribe of neighboring Burma (aka Myanmar).
When the missionaries fail to return, Rambo is persuaded to take a group of mercenaries back into the war-torn border region to find them. What follows is a descent into hell on earth.
Julie Benz, Matthew Marsden, Graham McTavish, Rey Gallegos, Jake La Botz, Tim Kang and Paul Schulze also star."