Until recent aerial surveys, the Guiana Highlands bordering Brazil were one of the few remaining unknown regions on Earth and were believed to house El Dorado and the fabled tribe of Amazon warrior women. The barrier of rapids pouring from the mountain has kept it almost unexplored. In 1950, Raymond Maufrais, a young French explorer, set off into the Amazonian jungle of the region and was never seen again. Fifty years later, inspired by Maufrais' diary, John and Heather Harrison took to the wildest and most remote tributaries of the Amazon with just a canoe and shotgun for company. They quickly have to adjust to an existence where they are dependent upon nature for food and upon each other for their sanity. With no means of contacting civilization, they are forced to realize the poignancy of Maufrais' final record. Unaided and off the map, they encounter jaguars and poisonous frogs, are threatened by malaria and almost lose their way entirely. All the while they struggle to keep their relationship intact in this most inhospitable of places.