As a Category 5 hurricane approaches Florida, college swimmer Haley Keller receives a call from her sister, expressing concern that their father Dave has not been answering his phone. Despite evacuation orders, Haley decides to check on her estranged father, driving through the deserted streets to their old family home. Upon arriving, she discovers her father severely wounded in the house's crawl space. With communication lines down and the storm intensifying, Haley attempts to move her father to safety but discovers the rising floodwater is the least of their worries.

Trapped below the house with no way out, Haley and Dave are terrorized by a pack of enormous alligators that have infiltrated the crawl space via a storm drain. The predators are relentless and fiercely intelligent, exploiting the flooding and hurricane to hunt their prey. While the water level continues to rise, so does the tension, as Haley must use her wits and her swimming skills to navigate the hazardous environment, outmaneuver the alligators, and save her father, all while the very foundation of their sanctuary threatens to collapse around them.