Kate (Halle Berry) is a shark expert whose business has been failing since a shark attack killed a fellow diver under her command. Once dubbed the shark whisperer, Kate is haunted by the memory of the attack and unable to get back into the water. With bills piling up and the bank about to foreclose on Kate's boat, Kate's old flame Jeff (Olivier Martinez) presents her with a lucrative opportunity: lead a thrill-seeking millionaire businessman on a dangerous shark dive outside the cage. Battling her self-doubts and fear, Kate accepts the proposal - and sets a course for the world's deadliest feeding ground: Shark Alley.