A couple of seaplane enthusiasts, Kaz Fellows and her partner Charlie Brody, set forth on an enchanting journey to the idyllic Hell's Reef, accompanied by their passengers—Joji Minase, his wife Michelle, and their cook Benny. Their idyllic flight takes a dark turn when they stumble upon a lifeless body, a victim of a suspected shark attack. Though they promptly alert the coast guard, they are deeply unsettled to find a picture of the deceased man's girlfriend on his phone.
Driven by a mix of curiosity and concern, Benny and Charlie persuade their companions to seek out the yacht the couple had been aboard, hoping that the girlfriend might still be alive. Despite Joji's protests—believing the search to be futile and perilous—Kaz pilots the group out to locate the damaged yacht. Unfortunately, they discover the vessel capsized, and Benny dives in to examine it for survivors. His grim discovery of the girlfriend's partially devoured corpse sends them racing back to the seaplane, only to be ambushed by the ferocious great white shark lurking nearby.
As their seaplane begins to sink, all five passengers scramble for the life raft, only to find themselves adrift in an unforgiving sea. In a desperate attempt to navigate to safety, Charlie relies on the raft's rudimentary compass and oars. Exhaustion takes its toll, and when Michelle dozes off, she inadvertently loses one of the precious oars. In a risky maneuver, Kaz jumps into the water to retrieve it. Tensions escalate as jealousy flares between Benny and Joji, leading to a tragic confrontation where Benny is ultimately killed by the shark. The relentless predator then turns its wrath on the raft, flipping everyone into the water—Joji included, who meets his own demise while attempting to swim back.
Stranded with no supplies and a single oar, Kaz, Michelle, and Charlie make a valiant effort to use their hands to paddle. Just when they thought things couldn't get worse, it becomes clear that they are now being targeted by multiple sharks. In a heart-stopping moment, Kaz is thrown overboard but manages to return to the raft unscathed. The following day brings distress when they spot land, yet they also realize their raft is losing air rapidly. Faced with the possibility of sinking and being at the mercy of the sharks, Kaz and Charlie devise a plan to distract the creatures while Michelle attempts to reach shore.
In a shocking revelation, Kaz, who is pregnant with Charlie's child, bravely strikes one of the sharks with a flare, while Charlie attempts to pierce its eye with a knife, effectively killing it. Meanwhile, Michelle manages to find refuge on a rusted fragment of shipwreck. As Charlie reloads another flare to deal with the remaining shark, tragedy strikes. Amidst a frantic struggle, Charlie is attacked and killed, leaving Kaz and Michelle to fend for themselves. Desperate, Kaz distracts the shark yet again, allowing Michelle to swim for safety.
Kaz finds herself trapped in the wreckage as the shark lunges at her. On the verge of losing consciousness and drowning, she is miraculously revived by Michelle through mouth-to-mouth resuscitation. Fueled by adrenaline, Kaz shakes off her near-fatal encounter and manages to repel the shark by dislodging debris that ultimately kills it. With their harrowing battle finally over, Kaz and Michelle swim to shore, each reflecting in silence on their extraordinary and perilous escape from terror.
