A young woman, Nancy, mourning the loss of her mother, seeks solace by visiting a secluded beach in Mexico, her mother's favorite escape that she fondly refers to as her "secret." An avid surfer, Nancy takes to the waves in a bid to reconnect with her mother's memory and find some peace. During her surf session, she meets two other locals who share the waves but soon leave as the day wears on. Relishing the solitude, Nancy decides to catch one last wave, but in doing so, she stumbles upon the carcass of a large humpback whale and becomes the target of a great white shark's attack.

Wounded but determined, Nancy finds temporary sanctuary atop the whale carcass but is quickly forced to move onto a small, isolated rock outcrop as the tide rises, and her makeshift refuge submerges. Just 200 yards from shore, she faces a battle of wits and will against the relentless predator patrolling the waters between her and safety. With limited resources and nursing a painful injury, she must strategize her escape, not just from the shark, but also from the elements, fatigue, and the onset of cold shock as day turns to night, and her hopes of rescue dwindle. Her fight for survival becomes a test of human endurance and resilience in the face of a seemingly insurmountable challenge.