Seventy years ago, Chester Bowie, a genius driven to madness, unlocked the mystery of how a weapon of unimaginable lethality allowed one man and his small army to conquer so much of the ancient world. The secret, however, died with Bowie in a fiery disaster that was no accident. Yet a series of cryptic clues were left behind, clues that geologist, and sometime government operative, Philip Mercer must follow if he is to prevent terrorists from unleashing the weapon on today's world. On the front lines of an African civil war, a chance meeting between Mercer and Cali Stowe, a researcher for the Centers for Disease Control, propels the two of them into the epicenter of the greatest act of terrorism ever conceived.