In a fictitious Latin American country, the soldier of fortune Sgt. McCall leads the Vargas Expedition sponsored by the powerful Harry Vargas and formed by the archaeologists Dr. Felicia and Lin; the local Santiago Zavala and a baggage carrier through the jungle. In the base, Carla Manning gives support to McCall's team and is the liaison with Harry, who is obsessed for a dagger. When they reach a tomb facing south in a sacred ground, they open the tomb and finds a dagger with a ruby craved in a skeleton and Lin removes weapon from the grave, accomplishing the objective of their assignment. Dr. Felicia advises them that the tomb has a warning advising to not remove the dagger. Soon they discover that nature and the Yamballi tribe are chasing them; further, the previous expedition sent to the forest to retrieve the dagger has been slaughtered.