Peter Clark and his wife Brenda have been working too hard lately and need a vacation. As Americans living in La Paz, Bolivia, Pete works as a freelance photographer and Brenda as a writer and illustrator of children's books. So, to escape the pressures of their work, they decide to travel to the central, Cochabamba region of Bolivia and relax at a picturesque inn nestled in the remote Yata Valley.While there they plan a hike to a hidden waterfall in the lower part of the valley. Pete and Brenda puzzle at the reluctance of locals in the nearby town of Todos Santos to offer directions to the waterfall or guide them there. The area is infested with snakes, Pete and Brenda are warned. Finally, they meet an old man, Sr. Hidalgo, who agrees to show them the way to the waterfall. On their early morning hike to the waterfall Sr. Hidalgo tells them that some years ago the lower Yata Valley, including the area around the waterfall, was the domain of narcotraficantes, cocaine dealers. These are the "snakes" the residents of Todos Santos were referring to. But five years ago the government swept the narcos out of the Yata Valley. The farmers who were terrorized by the narcos, however, have been reluctant to return to the valley. So the area around the waterfall is now completely uninhabited.But, while enjoying the tranquility of the waterfall, Pete and Brenda find out there are people in this part of the valley. Six men in ragged fatigues and peasants' clothes, invade their relaxing vacation and turn it into a cruel nightmare. The men wound Pete and Sr. Hidalgo, then kidnap Brenda and carry her deep into hostile territory. She fights to escape this mysterious band and their leader, Javier Guzmán, a man who knows more about Brenda than she ever dreamed and wants her for his own sexual pleasure before killing her.