From the depths of the Indian Ocean, a horrific plague has arisen to devastate humankind--unknown, unstoppable . . . and merely a harbinger of the doom that is to follow. Operatives of the shadowy covert organization Sigma Force, Dr. Lisa Cummings and Monk Kokkalis search for answers to the bizarre affliction aboard a cruise liner transformed into a makeshift hospital. But a sudden and savage attack by terrorist hijackers turns the mercy ship into a floating bio-weapons lab. Time is an enemy as a worldwide pandemic grows rapidly out of control. As the seconds tick closer to doomsday, Sigma's commander, Gray Pierce, must join forces with the beautiful assassin who tried to kill him--following the trail of the most fabled explorer in history into the terrifying heart of an astonishing mystery buried deep in antiquity and in humanity's genetic code.