A pharmaceutical research facility in the heart of Venezuela's Amazon Basin goes silent without warning. Primordial beasts never before seen by human eyes annihilate the team sent to investigate. Human eyes. The creatures have human eyes. When a newly discovered, but exceedingly rare plant specie shows promise as a possible cure for cancer, pilot Austin Stewart is ordered to accompany the alluring biologist Olivia Dover and her team of researchers to retrieve another specimen. But as the expedition journeys into the rainforest's shadowy depths, they quickly find themselves hunted by the same creatures that slaughtered the rescue team years before-beasts the local Yanomami tribesmen call 'hekura'. Evil spirits. But these are no mere apparitions. The research team, forsaken by those that sent them and racing against a Colombian drug lord to recover the precious catholicon, must fight for survival against ravenous mutants too strong to overpower, too intelligent to outsmart. The jungle guards its secrets fiercely.