The Amazon is a freaky place.

The world around me is utterly alive, and as we make our way by Jeep over the badly mangled roads of Brazil's interior forests, I feel the sensation of being inside a massive living organism — which, of course, I am.

It's the kind of environment where, no matter how prepared you are, it doesn't take much for the tables to turn. This is one of the last great wildernesses on Earth — a billion acres of seemingly endless jungles and rivers, ready to pitilessly envelop anyone who missteps. Here, in one of the most species-rich areas of the planet, one doesn't have to travel far to come up against nature's most dangerous predators. In fact, we're looking for one of them.

As I scan the blur that's passing by the windows, I can make out rows of scarred trees, bled by rubber-tree workers who toil deep in the rainforests to collect their precious sap. Natural latex has been harvested in the Americas for nearly 3,500 years, and the workers here who carry on this tradition often work in small, isolated groups. Alone within the mighty rainforests, these laborers have been telling tales for centuries of a creature called the Mapinguary.