Rae Ingram is involved in a car crash which results in the death of her young son. Her older husband,
Royal Australian Navy officer Captain John Ingram, suggests that they head out for a vacation alone on their yacht, the
Saracen. In the middle of the
Pacific Ocean, they encounter a drifting
schooner that seems to be taking on water. A man rows a dinghy over to the
Saracen for help. He introduces himself as Hughie Warriner and tells them the schooner is sinking and that the other passengers have all died of food poisoning. John rows to the schooner, the
Orpheus. Inside, John discovers the mutilated corpses of the other passengers and video footage indicating that Hughie may have murdered them. On the
Saracen, Hughie awakens, knocks out Rae, and sails it away. Left behind, John attempts to keep the
Orpheus from sinking and catch up with the
Saracen. Rae awakens, and John reaches her on the radio, but water damage makes him unable to reply except through clicks on the radio receiver to signal yes or no to her questions. Hughie tries to convince Rae to be friends with him. Rae accepts, attempting to earn his trust. John tells her that the
Orpheus is too far gone and will sink within hours. To save John, Rae plays along with Hughie's overtures long enough to get to the shotgun on the deck. She and Hughie start to kiss and undress, before Rae stalls for time by saying that she has to go to the bathroom. She runs onto the deck to assemble the shotgun, but her dog Ben follows her and starts barking, causing Hughie to investigate. In a panic, Rae leaves the gun behind. She returns to the bedroom, where Rae reluctantly has
sex with Hughie. Afterward, Rae fixes some
lemonade spiked with a heavy dose of her prescription sedatives and tricks Hughie into drinking it. Claiming she is going to get dressed, Rae returns for the shotgun, but Hughie discovers her and they grapple for the gun as a storm approaches. Hughie gains control of the shotgun, but the effects of the sedative cause him to aim poorly and shoot out the
Saracen's radio. Rae finds a harpoon launcher and locks herself in the bedroom. Hughie starts forcing the bedroom door and Rae fires harpoons through it, but hits and kills Ben, who was on the other side. Hughie bursts out of hiding to strangle her, but passes out from the drugs. Rae ties him up and sails back to rescue John. Hughie regains consciousness, cuts himself loose and comes after Rae, who shoots him in the shoulder with a harpoon and knocks him unconscious again. She sets him adrift in the yacht's life raft. The damage and the storm have caused the
Orpheus to fill almost completely with water, leaving John locked in the hold and struggling to breathe through a pipe. He finally breaks free after kicking through the hull and sets the wrecked
Orpheus on fire so Rae can find his location. At dusk, Rae notices the flames and eventually finds John on a piece of floating debris. She pulls him back on board the
Saracen, and they come upon the floating life raft, which Rae incinerates with a flare. The next day, John washes Rae's hair and prepares breakfast for her. While he is below decks, a gravely injured Hughie appears and begins to strangle her. While Rae struggles against him, John shoots Hughie in the mouth with a flare, killing him. Rae and John embrace as they sail away, leaving Hughie's body behind. ==Cast==