It has taken a long time, but humankind has won its battle against the sea. Now Professionals like Walter Franklin patrol the infinite savannahs of the oceans, harvesting from the plankton prairies. But like that other great frontier, space, the sea has not yet yielded up all its secrets. And men like Franklin will never rest until its every fathomless mystery has been challenged....
The first message sent to Tom Thorne's phone was just a picture - the blurred image of a man's face, but Thorne had seen enough dead bodies to know that the man was no longer alive. But who was he? Who sent the photograph? And why? While the technical experts attempt to trace the sender, Thorne searches the bulletins for a reported death that matches the photograph. Then another picture arrives.