Oilman Paul Sturges' idyllic family vacation turns into a nightmare when they encounter a ferocious megalodon shark that will stop at nothing to protect its territory. Stranded and under constant attack, Paul and his family must somehow find a way to get his family back to shore alive before it strikes again in this epic battle between humans and nature.

DEA agent Jerry Simms and cellmate Chato plot to expose a prison drug ring when a monstrous Black Demon attacks. Crime boss Diego releases rival sea creatures, leading to a battle of beasts at the polluted facility.