Cassidy, a marine biologist haunted by her father's death by a shark, decides to confront her fears by embarking on a diving expedition with her new husband, Gregg, near Madagascar. They are also hoping to find sunken treasure. Their boat, captained by Gregg's friend Daemon, also includes other divers, including a couple named Pierre and Itsara. However, their trip takes a dangerous turn when modern-day pirates, led by the sociopathic Jordan, seize their boat, looking for a lost shipment of drugs. The pirates force the tourists to dive into shark-infested waters to retrieve the contraband. As the divers struggle to survive, they encounter both the deadly sharks and the ruthless pirates.