In 1559, forty-nine Spaniards exploring a tributary of the Orinoco River reached a sheer-sided, cloud-capped mountain called Tepui Zupay. When they tried to climb it, all but six died -"slaughtered by Amazons," claimed Friar Sylvestre, the expedition's chronicler. Jerry Pace, a burn-scarred botanist struggling for tenure at UCLA, thinks the friar was high on mushrooms. Jerry's best friend, Hector, the historian who acquired Sylvestre's journal, disagrees. He plans to retrace the expedition's footsteps, and wants Jerry to come with him. Jerry is reluctant, until he spots a stain between the journal's pages - a stain that could only have been left by a plant that died out with the dinosaurs. Now he has to find that plant. But the Venezuelan wilderness does not forgive intruders. Battered and broken, they reach a remote Catholic orphanage, where the old prioress warns of death awaiting any who would venture farter. But an exotic indian girl leads them on through piranha-infested rivers and jungles teaming with poisonous plants, to Tepui Zupay - the forbidden mountain no outsider has seen since the Spaniards met their doom.