一年一度的春假到来,来自全国各地的大学生纷纷涌向度假胜地维多利亚湖,他们纵情歌舞,寻欢作乐。青年杰克·福斯特(史蒂芬·R·麦克奎恩 Steven R. McQueen 饰)追随友人来到海边。在电视人德里克·琼斯的邀请下,杰克和心仪的女孩凯莉(杰西卡·斯佐尔 Jessica Szohr 饰)等友人登上了德里克的游艇。在一个幽静的角落,女孩们尽情游水,享受美好的时光,却不知危险正慢慢逼近。 原来近期湖底的地壳发生变动,一群在史前时代因火山爆发而被困在湖底的恐怖食人鱼重返人间,它们纷纷向毫无防备的人类发起猛烈攻击。秀美宜人的湖泊一瞬间变成血腥残酷的修罗场……Lake Victoria's annual Spring party by 50,000 young revelers is about to turn into a feeding frenzy with prehistoric hunger-pains. With knee-trembler's above the waves and tremors below, released from their dormant sleep, thousands upon thousands of flesh-eating nippers are released into the lake with whetted appetites and razor-sharp teeth. With a motley crew of strangers thrown together to defend these shores, it is now up to them to prevent the largest eat-out in human, and piranha, history.