Shortly after the death of her mother from
cancer, medical student Nancy Adams travels to a secluded beach in
Mexico, the same one her mother visited while she was pregnant with her. Carlos, a friendly local resident, gives her a ride and drops her off alone at the beach, as her friend who came along with her is staying back at their hotel, recovering from excessive partying. Nancy joins two other locals and the three surf for several hours. Taking a break from surfing, she video-chats with her younger sister Chloe. When she talks to her father in an emotional and strained conversation, it is revealed that Nancy is a senior student but her mother's recent death has caused her to consider dropping out of medical school before graduation. While surfing one last time for the day, Nancy notices the carcass of a young
humpback whale nearby. As she rides the last wave back to the beach, a large
great white shark knocks her off her surfboard and bites her leg. Nancy climbs onto the whale carcass, but the shark rams it from underneath. She is knocked off but is able to swim to an isolated rock. She uses her surfboard leash to slow the bleeding from her leg. Later, she uses her jewelry to put rudimentary stitches in place to hold her torn flesh together and the sleeve of her wetsuit as a compression bandage. Nancy is left alone when the unaware locals leave the beach, and she spends the night on the rock with a wounded gull, also injured by the shark, and names him
Steven Seagull. The next morning, she gets the attention of a drunk local man on the beach and points to her backpack on the beach. When he finds it, he starts to steal Nancy's belongings, then wades out into the water to steal her surfboard and is killed by the shark. Several hours later, the two locals Nancy had surfed with the day before return. Although she tries to warn them away, they get into the water and are also killed by the shark. One of the local surfers was wearing a
GoPro camera on his helmet. When the shark attacked him, the helmet came off and floated to the surface. Nancy later sees it floating in the water. After some struggle, in which both she and the shark are injured by stinging coral, she is able to retrieve it. While watching footage of the attack, Nancy notices the shark has a large hook stuck in its mouth, possibly from an encounter with fishermen. She uses the GoPro to leave messages for her sister and father, as well as information about the shark attack, her injuries, and her location, although she does not know the name of the beach. With the high tide approaching, Nancy realizes the rock will soon be submerged. After sending Steven Seagull toward shore on a piece of the surfboard, and timing the shark's circles from the whale carcass to the rock, Nancy swims to a nearby
buoy, narrowly avoiding the shark by swimming through a group of
jellyfish, which sting both the shark and her. As Nancy finds a
flare gun on the buoy, she shoots flares to draw the attention of a faraway cargo ship. However, it has already turned away and does not see her. Nancy then fires another flare at the shark, setting the oil from the whale carcass alight and angering it, but otherwise it has no effect. The shark then ferociously attacks the buoy, ripping out the chains securing it to the ocean bed. Nancy straps herself to the last remaining chain and as it is ripped from the buoy, she is pulled down to the ocean floor, pursued by the shark. At the last moment, she pulls out of the dive, and the shark is impaled on
rebar protruding from the buoy's anchor. Later, a boy named Miguel (from the opening of the film at the beach) finds the GoPro and informs his father, who is revealed to be Carlos. Miguel spots Nancy floating close to shore and Carlos brings her ashore and revives her. As she recovers consciousness, she briefly sees a hallucination of her mother. As she looks around the beach, she sees that Steven Seagull has made it to the shore. One year later, a healed Nancy (now graduated as a doctor) and her sister Chloe go surfing in
Galveston, Texas, as their father tells Nancy that her mother would have been very proud of her for not giving up. ==Cast==