The complex ecosystem of the Amazon covers an area about the size of the continental US. Approximately one of every four flowering plant species on earth resides in the Amazon. A single Amazonian river may contain more fish species than all the rivers in Europe combined. The rain forest, which contains approximately 390 billion trees, plays a vital role in stabilizing the global climate by absorbing massive amounts of carbon dioxide - or releasing it into the atmosphere if the trees are destroyed. Severe droughts in both Brazil and Southeast Asia have been linked to Amazonian deforestation, as have changing rainfall patterns in the US, Europe, and China. The Amazon also serves as home to millions of people.

Approximately 70 tribes of isolated and uncontacted people are concentrated in the Western Amazon, completely dependent on the land and river. These isolated groups have been described as the most marginalized peoples in the Western hemisphere, with no voice in the decisions made about their futures and the fate of their forests. In this addition to the What Everyone Needs to Know series, ecologist and conservation expert Mark J. Plotkin, who has spent 40 years studying Amazonia, its peoples, flora, and fauna, offers an engaging overview of this irreplaceable ecosystem and the challenges it faces.