A documentary crew, headed by anthropologist Steve Cale (Eric Stoltz) and director Terri Flores (Jennifer Lopez), journeys to the depths of the Amazon in search of the mysterious Shirishama Indians. En route, they rescue a hunter (Jon Voight) from his sinking boat and take him on board. After the ship's captain is attacked by a poisonous insect and goes comatose, the hunter commandeers the boat, takes the crew hostage, and drags them along on his insane quest to capture a giant anaconda.