Commander David Grant is one of the US Naval Intelligence top investigators. He is sent to Mindanao in the Philippines to ascertain why the local community fishing boats are being attacked and destroyed by an unknown assailant. This is an embarrassment for the US government as Gopher Oil, the company that is supposedly searching for oil, is in fact a totally owned subsidiary of the US government and they don't want unwelcome government officials from Manila prying around the oil rigs. The reason for the concern in Washington is that 'The Project Pacifico Complex', which is situated under the Gopher oil rigs is intended to be the underwater refuge of The President in the event of a nuclear war. Pacifico would act as a safe haven and command facility for The President and government of the United States should there be an unprovoked nuclear attack from its enemies. Grant runs up in his investigations, against 'The Moro National Liberation Front' guerrilla group intent on thwarting his investigations. The MNLF make several attempts both by assassination and ambush to speed up Grant's demise. In the background there is an even more sinister group whose aims seem to run along the same guidelines as the MNLF. A beautiful Filipina government official Pilar Oracca, is sent down from Manila to determine if a giant shark from mythology 'Megalodon' is responsible for the attacks on the craft or some other entity. Betrayal and subterfuge encounter David Grant on all sides. However, what is the purpose of fabricating Megalodon's existence if the monster shark does not exist? Grant however, is certain of one thing that if this 100 ton behemoth from the Pliocene period exists it would make a formidable and terrible adversary. Twenty miles north west of the rigs the massive grey shape of the thing known as Megalodon cruised the deeps, its belly saturated with the life blood of men, its cold brain centres alert to crush and destroy. Lesser scavengers of the sea shied away, as the huge bulk of this nemesis cut a swathe of annihilation through millions of micro-organisms. Underwater drags of current created by its passage scattered a shoal of tiny fish, which hurriedly regrouped as its mighty length disappeared into the black pit of the ocean.