As taken from the author website (www.jamesrollins.com):

The Rand scientific expedition entered the lush wilderness of the Amazon and never returned. Years later, one of its members has stumbled out of the world's most inhospitable rainforest: a former Special Forces soldier - scarred, mutilated, terrified, and mere hours from death - who went in with one arm missing...and came out with both intact.

Unable to comprehend this inexplicable event, the government sends Nathan Rand into this impenetrable secret world of undreamed - of perils to follow the trail of his vanished father...toward mysteries that must be solved at any cost. But the nightmare that is awaiting Nate and his team of scientists and seasoned U.S. Army Rangers dwarfs any danger they anticipated...an ancient, unspoken terror - a power beyond human imagining-that can forever alter the world beyond the dark, lethal confines of the Amazon rainforest for better... and for worse.