Researchers on the undersea lab Aquatica have genetically altered the brains of captive sharks to develop a cure for Alzheimer's disease. But there's an unexpected side effect: the sharks got smarter, faster, and more dangerous. After a big storm damages their remote research facility, they must fight for their lives.

When shark conservationist Dr. Misty Calhoun is invited to consult on a top-secret project run by pharmaceutical billionaire Carl Durant, she is shocked to learn that the company is using unpredictable and highly aggressive bull sharks as its test subjects, which soon break loose and cause havoc.

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.