In early 1980s, an Israeli adventurer named Yossi Ghinsberg travels to Bolivia planning to journey into the heart of the Amazon rainforest. There, he meets Marcus Stamm, a Swiss school teacher, and his friend, Kevin Gale, an American hiker and avid photographer. The three are staying in La Paz, at an Israeli community hostel. Yossi is out in the market one day where a stranger asks if he is an American; Yossi replies,”no”. During conversation the Austrian stranger, Karl Ruprechter, claims the existence of an Indigenous tribe in the jungle that they should go see. Karl says he knows the jungle, and he is friends with the tribe. Yossi, excited about the prospect of exploring the uncharted jungle and meeting undiscovered peoples like the Toromonas, chooses to believe him. He heads back to the apartment to convince Marcus and Kevin to come along. Skeptical of the stranger and his story, they refuse. Yossi continues to press them until they ultimately acquiesce. The next day, the trio meets Karl in a shop while he is gathering supplies for the hike. All three men are surprised when Karl leaves with the supplies and tells them they will pay for everything. Yossi, Marcus, Kevin, and Karl hike through the jungle for several days. They make it to a village where it is apparent Karl knows the villagers. They spend the day in the village and stay overnight, then head back into the jungle the next morning. Marcus starts having trouble walking, and it is discovered his feet are full of bloody sores. By now, Kevin and Yossi are tired of Marcus' complaining. Yossi, Kevin, and Karl discuss how they all should proceed. Karl wants to leave the three while he goes and gets help, but Kevin and Yossi disagree with that plan. At this point Marcus walks up, and Kevin proposes building a raft to navigate downriver, so all of them can stay together. They build a raft and set off down the river. They hit some rapids, barely making it through. Karl gets upset at Kevin for taking control on the raft, floats the raft to shore, and says he is going hunting. Kevin had noticed Karl's fear of water and deduces that Karl cannot swim. Yossi then goes to find Karl, so he will not abandon them. Marcus and Karl decide to abandon the journey and make the three-day hike back to La Paz. Meanwhile, Yossi and Kevin continue their journey downriver until their makeshift raft is destroyed in the rapids. Yossi is washed away by the river, leaving Kevin behind. Without a knife, tools, or any kind of survival training, Yossi must improvise shelter and forage to survive. He begins to give up hope after losing all sense of direction, wondering if he will ever survive the jungle. Meanwhile, Kevin is rescued by people from the local town who take him to Rurrenabaque, 120 miles from Yossi's location, Curiplaya. At Rurrenabaque, Kevin calls for the help of the local authorities to find Yossi. They fail to find Yossi via a plane flyover, but Kevin believes that Yossi is alive. Kevin ropes in the help of the local boat pilot to search for Yossi, finally discovers his weakened friend, and takes him to Rurrenabaque. The epilogue says that Karl and Marcus were never seen again and that Karl was wanted by the authorities.
On 10 February 2016, Daniel Radcliffe joined the cast. On 21 March 2016, Thomas Kretschmann and Alex Russell also joined the cast. Principal photography began on 19 March 2016 and ended on 13 April 2016.
The review aggregator website Rotten Tomatoes gives the film a rating of 60%, based on 48 reviews, with an average rating of 5.7/10. On Metacritic, the film has a score of 48 out of 100, based on 14 critics, indicating "mixed or average reviews". Writing for The A.V. Club, Alex McLevy gave the film a B−, praising Radcliffe's acting commitment and the shock of some of the scenes but wrote, "Unfortunately, the movie too often can’t resist leaning into the melodrama of the situation. Rather than allowing the power to come from the raw intensity of what transpired, it occasionally turns Ghinsberg’s journey into a Hollywood spectacle, making the incredible seem a little less so in the process." Dread Central's Jonathan Barkan gave the film 4.5 out of 5, saying that it was, "without a doubt, the most thrilling, exhilarating, and inspiring film I've seen this year."
