When Nancy is surfing on a secluded beach, she finds herself on the feeding ground of a great white shark. Though she is stranded only 200 yards from shore, survival proves to be the ultimate test of wills, requiring all of Nancy's ingenuity, resourcefulness, and fortitude.
After losing her mother, the medical student Nancy dumps the medical school in Galveston and travels to Mexico, hitchhiking to a hidden beach that her mother loved when was young. She brings a backpack and a surf board to surf and she meets two surfers that warn about the low and high tides schedule. They leave the sea, but Nancy decides to stay a little more. When she sees a dead whale floating on the water, she swims close to the animal and is surprised by a white shark. She is bitten on the leg and uses her medical knowledge to survive on a rock. But the high tide is coming and she is under siege of the ferocious shark.