Botswana's Okavango Delta is considered by many to be one of the last "Edens" left on Earth. There a rich assortment of organisms exist in natural equilibrium.

The same insults in microcosm - encroaching agriculture, water diversion, disease, and pollution - threaten the Okavango that in macrocosm threaten the entire planet. Starting with a sensual journey by plane and boat, Eldredge leads a reader first to the very heart of the Okavango, and then on a tour of Earth's organisms - animals, plants, fungi, and the microbes which underpin all of life - and ecosystems in which these organisms earn their living - from the tundra to the tropics.

It is a journey that reveals the twin faces of biodiversity (the 13 million extant species and the ecosystems through which these species transform and exchange the Sun's energy) and the value of biodiversity to the Biosphere as a whole and to our own continued human existence.

Eldredge's tour ends at the Panama Canal, the site of one of humankind's greatest achievements, where, if only by necessity, practical solutions to maintaining biodiversity's delicate balance have been successfully implemented. If his message is not entirely pessimistic, it is not entirely hopeful either. There are a number of difficult actions we must take as a global society if we are to stem an impending Sixth Extinction, and Eldredge outlines these steps in detail.