Young yachting captain Tim Whalen (Rob Lowe) is having an affair with Brooke Morrison (Kim Cattrall), the wife of his boss, Granger Morrison (Brian Davies), in the upscale town of Southampton, Long Island. Tim is the new captain of Granger\'s racing sailboat Obsession. Young heiress Olivia Lawrence (Meg Tilly), following the recent death of her mother, returns home to Southampton after graduating from college. At a party, Olivia is introduced to Tim, who asks her to dance. Impressed with her knowledge of sailing, Tim asks her to go sailing with him, and she accepts.
Olivia is living in the family mansion with her alcoholic stepfather, Tony Gateworth (John Glover), and his new live-in girlfriend, Anne Briscoe (Dana Delany). Her mother\'s will provided that Gateworth retain access to the family\'s eight properties. Olivia has nothing but contempt for her stepfather, who married her mother for her money. At her family attorney\'s office in New York City, Olivia learns she cannot restrict Gateworth\'s access to her homes, and the nearly one million dollars a year he receives from the estate barely covers his gambling debts.
Olivia and Tim go sailing on her boat Masquerade, which was her late father\'s pride and joy. Later, at Olivia\'s mansion, they are confronted by a drunk Gateworth who insults Tim, his former sailing competitor. In the coming days, Olivia and Tim begin dating and eventually fall in love. However, Olivia\'s newfound happiness is soon offset by another ugly confrontation with Gateworth who tells her as her \"guardian\" he wants Tim out of her life. Olivia confides to her aunt that Tim is the first man she has felt comfortable with and that he isn\'t interested in her money. Later that day, at a lobster house on the outskirts of town, Gateworth and Tim meet surreptitiously to discuss their conspiracy to murder Olivia for her money. When Tim expresses doubts, Gateworth threatens to expose his past. He tells him the next step is to gain Olivia\'s confidence by having Tim defend her against him.
That weekend, Olivia and Tim have passionate sex in the mansion. Afterwards, a drunken Gateworth breaks into Olivia\'s room as planned, but Tim double-crosses him and kills Gateworth with his own pistol. Believing they will be accused of murdering Gateworth, Olivia covers up Tim\'s role in the killing by claiming she killed Gateworth in self-defense. Tim establishes an alibi with an unsuspecting Brooke by resetting her bedside clock. During the investigation, Officer Mike McGill (Doug Savant)—a childhood friend with a romantic interest in Olivia—finds evidence that Tim may have been involved in the killing, but he does not report it to his captain, presumably because of his feelings for Olivia.
Gateworth\'s girlfriend, Anne Briscoe, begins questioning the investigation\'s findings, and tells the authorities about Olivia and Tim. Meanwhile, Tim breaks up with Brooke, who later confirms Tim\'s alibi to the police. Not long after Anne Briscoe informs McGill that her friend saw Gateworth at a diner with Tim, she is found hanged in an apparent suicide. McGill requests an autopsy.
While sailing aboard Masquerade, Olivia asks Tim to marry her, but he is reluctant, telling her he once spent 30 days in jail for writing bad checks. He also tells her about his affair with Brooke Morrison. His \"honesty\" convinces Olivia he is the right man, and the couple are soon married. Later, Olivia reveals she is pregnant. That night, Tim drives to the marina where he meets secretly with McGill, who was part of the original conspiracy—who in fact planned everything. Tim is reluctant about killing Olivia, but McGill insists she must die in a staged car accident. He threatens to put Tim away for Gateworth\'s murder if he doesn\'t cooperate.
When McGill learns that Tim has no intention of killing Olivia and that they are planning to sail for Florida on Masquerade the next day, he sabotages Olivia\'s sailboat and plants incriminating evidence in Tim\'s linen drawer. Tim discovers McGill\'s treachery and races to the marina to save Olivia, but is killed in the gas explosion meant to kill Olivia. In the marina office afterwards, Olivia discovers a newspaper clipping with a picture of Tim, Gateworth and McGill, just as McGill enters the office. Seeing that she has figured out the conspiracy, he tries to kill her. In the ensuing struggle, Olivia pushes McGill out a window causing his death.
At Tim\'s funeral, Olivia learns from her family attorney that Tim recently insisted he be removed from Olivia\'s will, and however it may have started, he came to love Olivia in the end.
