Knifeless, gunless, and face-to-face with a jaguar, Yossi Ghinsberg is not merely deep in the jungle, he's in deep trouble. What begins as a dream adventure for four amicable if hastily met muchileros (backpackers), quickly becomes dangerous as they unravel under the duress of travel. They are an odd mix, to be sure: Marcus, the frail Swiss mystic; Karl, the shifty Austrian geologist with a shady past; Kevin, the well-intentioned American photographer; and Yossi, the Israeli dreamer and eager explorer.

Setting out from La Paz, Bolivia, the foursome flies to Apolo, the most remote area of the rainforest accessible by plane. From there they set off on foot in search of the Incan gold and Indian villages that Karl promised they would find. After weeks of wandering in the dense undergrowth, Marcus's health seriously deteriorates and relations reach a breaking point; the four split up.

Karl and Marcus hope to cut a path back to civilization and Yossi and Kevin decide to continue by raft down the Tuichi River, a source tributary of the Amazon. The swift and treacherous current throws their craft against a large rock, pinning them in place. Kevin fights the current to shore. Yossi clings to the raft as it is suddenly jolted free and careens toward the Mal Paso San Pedro, a canyon of sheer rock faces that ends in precipitous falls.

Narrowly escaping death, Yossi enters an even greater ordeal: He finds himself alone save for the company of lora snakes, fire ants, termites, jaguars, and other unwelcoming neighbors for the next three harrowing weeks. What follows is the story of Yossi's triumph over the most adverse and frightening of circumstances, and Kevin's determined search for him. This is a tale of survival and human fortitude against the wildest backdrop on the planet.