When missionaries in Myanmar disappear into the vast green inferno, vigilante Vietnam War veteran John Rambo leaves his job as a Salween River boatman behind to accompany a group of mercenaries on a daring rescue mission. It's been twenty years since Rambo traded his guns for a fishing reel, but the world's longest running civil war rages into its sixtieth year on the nearby Thai-Burma border. Now, despite the fact that Rambo has long since sworn off all forms of violence, the knowledge that innocent missionaries are being used as pawns in a brutal war leaves him with no other choice than to venture behind enemy lines on his most dangerous mission to date.