Upon his return to Comeback Bay, Jamaica, Pat Fairlie, a former American Navy officer who now operates a modest shipping business, visits old flame Ena Dacey at her hilltop plantation home, Great House. Although Ena and Pat are still in love, Ena's devotion to her eccentric, alcoholic mother and ne'er-de-well brother Todd has kept them from marrying. At dinner that night, Todd and Mrs. Dacey boast about their wealth to Judge Henley and William Montague, a real estate developer who wants to buy an acre of Mrs. Dacey's beach. Despite the family's failing finances, Mrs. Dacey refuses to sell, and after the meal, Pat tells Ena that her mother and brother are absurd poseurs. Ena defends her family and orders Pat to leave. Pat offers Henley and Montague a ride back to Kingston on his schooner, The Dolphin , and during the trip, Henley, who visits Great House annually to collect its £1 rent, tells Montague the story behind the sugar plantation's unusual lease: One hundred years before, Mrs. Dacey's ancestor intended to sell Great House to another Dacey, John, while sailing on the bay, but when the boat sank in a storm, all evidence of the transaction was lost. Because of the plantation's uncertain ownership, the original Daceys and their heirs were permitted to remain at Great House as renters, paying a token sum each year. His curiosity piqued, Montague decides to track down John Dacey's heirs when he returns to New York, advertising in papers across America. Sometime later, Montague approaches Pat about using The Dolphin to locate the sea chest containing the sale papers, hoping to prove that John Dacey did indeed purchase the plantation and that siblings Janice and Robert Clayton, John's descendants, are the rightful heirs. Pat at first refuses to participate, but changes his mind when Montague points out that Pat can better protect Ena by becoming involved. When Montague introduces the Claytons to the Daceys at Great House, Todd and Mrs. Dacey are shocked by the possibility of losing their home and question the legitimacy of the Claytons' claims. After Janice angrily insists they have documentation, Todd apologizes and invites the Claytons to stay at the house. Attracted to Janice, he then gives her a tour and suggests they explore Pirates' Cave. On The Dolphin , meanwhile, Pat dives in search of the chest but finds nothing. That night, as a storm rages, the Daceys, Pat and Montague realize that Todd and Janice, who cannot swim, are trapped in the cave and rush to save them. Todd is swimming to shore when they arrive, but Pat must drag the terrified Janice out of the cave before it is completely flooded. Although Janice declares that Todd did everything he could to help her, Montague, who hopes to marry Janice, accuses Todd of attempted murder. The next day, Pat resumes his diving and, to his horror, finds Robert dead on the sea floor, wearing Pat's spare diving suit. Inspector Tom Mole is called in to investigate and rules Robert's death a murder. That evening, Mole questions Pat and the residents of Great House, and Mrs. Dacey coyly suggests that Pat is the killer. Ena and Pat, who have made up, then drive to a native cafe for a drink and witness a voodoo ceremony being conducted by Human, Mrs. Dacey's faithful butler. Although Pat dismisses voodoo as superstition, Ena is disburbed and asks to leave. At Great House, meanwhile, Todd talks the grieving Janice into joining him for a horseback ride, and while stopped on the beach, starts to propose to her. Before she can respond, her horse takes off, eventually throwing her. At the same time, Ena and Pat are driving back to the house when they spot a man in a diving suit wading into the bay. Later, diving from The Dolphin , Pat finds the mystery diver standing over a chest and is attacked. After his assailant cuts his airhose and flees, Pat is rescued by his crew. Pat and Ena follow the diver's wet footprints back to Great House but cannot determine their source. The next day, Pat retrieves the abandoned chest and, just before it is opened, Todd proposes again to Janice, who is recovering from her fall. Janice accepts, claiming not to care anymore about owning Great House. When Janice learns that Todd was aware of the chest's discovery and said nothing to her, however, she accuses him of manipulation and rejects him. To Mrs. Dacey's consternation, documents in the chest reveal that John Dacey did in fact purchase the plantation, and Montague and Janice prepare to take over Great House. Suspicious, Pat sneaks the papers out and drives to Kingston with Ena, where he visits several merchants. Later, during a hearing to determine ownership of Great House, an antique dealer called by the Daceys' lawyer testifies that he recently sold the chest to an unknown buyer, and a self-confessed forger admits that Montague paid him to create the sale papers. Thus implicated, Montague, the mystery diver, is arrested for fraud and Robert's murder. Pat and Ena, and a reunited Janice and Todd return happily to Great House, but find it consumed in flames. Rushing inside, Todd and Pat fight off Human, who set the fire with Mrs. Dacey's blessing, and rescue the dazed matriarch. Later, with their property secure, Mrs. Dacey, Todd and Janice contemplate rebuilding, while Ena and Pat finally sail off together.