There is something swimming beneath the placid surface of Caribbean waters -- something sleek and frightening, an inexplicable perversion of the natural order.

Virgin Islands charter captain David Hope has seen it, and his passenger, beautiful renegade filmmaker Sally Moffitt, has captured its image. Now they have something that one man will do anything to possess. William Tree, the commander of a towering high-tech research vessel and scion of one of America's wealthiest, most powerful families, lives his life in single-minded pursuit of a dark and brilliant vision that the world will soon recognize . . . and fear. But Hope and Moffitt cannot trust this amiable, eccentric, and dangerous man. And they intend to keep their secret hidden, even as a nightmare, uncontained, rises up from the depths, setting them off on a breakneck hunt for answers to the greatest and most devastating mystery the seas have ever nurtured.

A mystery that is now, ruthlessly and relentlessly, hunting them . . .