神秘小岛,异形乍现吓破胆。半人半鲨,惊天动地噬人头!三十年前,在设有美国海军调查站的鲨齿岛上,一条变种的大白鲨肆虐后逃往大海,消失得无影无踪。现在海洋生物学家查斯搏士,跟他的妻阿曼达及儿子麦斯,同时在鲨齿岛上工作,没想到非比寻常的事情正等待着他们。在一次的海上行程中,三人被怀疑是大白鲨类的物体袭击,令船只受到严重破坏,三人幸保性命!他们相信袭击自己的并非普通的鲨鱼,可是除了酗酒的老伯狼人之外,这种说法完全无人相信……An amphibious shark-like monster terrorizes an abandoned secret military base and the people who live on the island it is located on. A marine biologist, as well as several other people, try to stop it before it is too late...