From #1 New York Times bestselling author James Rollins, the latest riveting, deeply imaginative thriller in the Sigma Force series, told with his trademark blend of cutting-edge science, historical mystery, and pulse-pounding action.It begins in Africa . . .  A United Nations relief team in a small village in the Congo makes an alarming discovery. An unknown force is leveling the evolutionary playing field. Men, women, and children have been reduced to a dull, cattle-like state. The natural world surrounding them—plants and animals—have grown more cunning and predatory, evolving at an exponential pace. The insidious phenomenon is spreading across the African continent, threatening the rest of the world. But is it a natural event? Or more terrifyingly, did someone engineer it? What has made the biosphere run amok? Commander Gray Pierce and Sigma Force are prepared for the extraordinary and have kept the world safe—vigilance for which they have paid a tragic personal price. Yet even these brilliant and seasoned scientific warriors do not understand what is behind this frightening development—or know how to stop it. As they race across the nation and around the globe—from Washington D.C. to the densest jungles of Africa—to find answers, the members of Sigma realize they have become prey.  To head off global catastrophe, Sigma Force risks their lives to uncover the shattering secret at the heart of a biosphere run amok—a truth that will illuminate who we are as a species and where we may be headed . . . sooner than we know.  Mother Nature—red in tooth and claw—is turning against humankind, plummeting the entire world into The Savage Zone.