在太平洋范围内,一批探测员乘坐轮船打算去海洋深处探测,正在他们进行任务对接时,船上人员监测到深海附近有不明障碍物靠近,他们紧急联系入海人员,但最终发生了惨剧,海底监测人员被鲨鱼所食。六个月后,在墨西哥靠近太平洋的海岸港口附近,鲨鱼又出现了,人们并不知情。一个爱好潜水的年轻人在海水中发现了一枚鲨鱼的牙齿。这枚牙齿引起了年轻人的兴趣,他开始寻找相关的资料。而鲨鱼真的会再次出现在墨西哥的港口吗?人们的生命将会受到威胁吗?Dr. Emma Collins and her team are spending their third summer on the island of Little Happy studying the effect of climate change on the great white sharks who come to the nearby nursery every year to give birth. Along with the last two inhabitants of this former fishing village, their peaceful life is disrupted when a "scientific" team led by her ex-boyfriend and marine biologist Richard show up looking for three bull sharks who we soon learn aren't just any bull sharks.