A ticking-time-bomb insomniac and a slippery soap salesman channel primal male aggression into a shocking new form of therapy. Their concept catches on, with underground "fight clubs" forming in every town, until an eccentric gets in the way and ignites an out-of-control spiral toward oblivion.

Ford Brody, a Navy bomb expert, has just reunited with his family in San Francisco when he is forced to go to Japan to help his estranged father, Joe. Soon, both men are swept up in an escalating crisis when an ancient alpha predator arises from the sea to combat malevolent adversaries that threaten the survival of humanity. The creatures leave colossal destruction in their wake, as they make their way toward their final battleground: San Francisco.