On the rebound after a devastating break-up, Lisa is ready for adventure while on vacation in Mexico with her sister Kate. Soon, the girls join a shark-diving excursion on a boat. Lowered 16 feet into the Pacific Ocean in a rickety cage, Lisa and Kate catch a once-in-a-lifetime, close-up look at a group of majestic Great Whites. But suddenly, the cage breaks away from the boat and plummets 47 meters down to the seabed. With their oxygen supplies rapidly dwindling, and surrounded by the ocean’s fiercest creatures, the girls will have to attempt everything to survive.