During a Florida heat wave, lawyer Ned Racine watches from his window as a building burns in the distance, then returns to bed with his lover. The next day in court, the Judge orders Ned to make a deal with Assistant Prosecutor Peter Lowenstein since Ned presented such a bad defense for his client. That night, Ned wanders the boardwalk and stops at a bandstand. Intrigued by a beautiful woman leaving the show, he follows her and tries to engage her in conversation. Matty Walker is married and not looking for company, but Ned jokes that she should have said, “happily married.” Ned learns that Matty lives in Pine Haven with her husband, who only comes home on weekends. When Matty spills liquid on her blouse, Ned goes to get a wet cloth, but returns to find her gone. Later, Ned finds Matty alone at Pine Haven Tavern. They talk about the heat and she offers to show Ned her wind chimes, but she does not want anyone to suspect an affair, so they leave separately. At Matty’s home, it is the maid’s night off, so they are alone as Matty shows Ned the chimes, and points out the gazebo and boathouse. Asking Ned to leave, Matty kisses him goodnight and closes the door, but Ned turns back, breaks through the door, and they make love in the hallway. They continue to see each other, although Matty insists no one else can know. Later, at lunch with Lowenstein and local police officer Oscar Grace, Ned is teased that he has never before been silent about his conquests. When Matty’s husband, Edmund, leaves at the end of the weekend, Ned returns to the mansion and rushes up to “Matty” in the gazebo; however, the woman is not Matty, but a close look-alike. Matty comes outside to join them and introduces her friend, Mary Ann, to Ned. Matty hands an envelope to Mary Ann and the woman leaves. Later, Matty talks about her husband’s will and Ned learns that, among Edmund’s businesses, he owns shore-front properties, including a place called The Breakers. As Matty expresses fear of her husband and wishes him dead, Ned suggests that she leave Edmund, but Matty confesses that she signed a pre-nuptial agreement and that will not get her much money in a divorce. That weekend, Edmund brings home his niece, Heather Kraft, who will be visiting for the week. Matty tells Ned to stay away, but he surprises her late one night after Heather has gone to sleep. As they make love on the porch, Heather comes outside, sees them and runs back into the house. However, Heather does not say anything about the event and leaves with her mother, Roz, on Thursday as planned. At a local restaurant, Ned runs into Edmund and Matty, who introduces the two men, pretending not to know Ned’s first name. Edmund insists that Ned join them, and, when Matty excuses herself, Edmund admits that if Matty was adulterous, he would kill the lover with his bare hands. The next day, Matty sneaks into Ned’s office and admits that she loves him. Ned plans to kill Edmund so Matty will inherit half of his estate. Matty complains that Heather will also inherit half of Edmund’s estate, but that Roz will certainly take her daughter’s money. Matty suggests that Ned covertly rewrite Edmund’s will. Ned refuses because it would look suspicious, and Matty agrees. Sometime later, Ned meets with a former client, Teddy Lewis, who gives Ned a bomb. The next day, Ned drives to Miami and meets a client regarding a real estate deal, but leaves his car in the city and drives back to Pine Haven in a rental car. Hearing an intruder downstairs, Edmund grabs a gun and investigates. Matty yells a warning, and Ned attacks. The men struggle until Ned bashes Edmund’s head with a board. Ned wraps the body in plastic and drives Edmund’s car to The Breakers. There, Ned dumps the body inside, and sets the bomb. Just before it explodes, Matty picks up Ned and they escape. Days later, Ned gets a call from Miles Hardin, Edmund’s lawyer, who says that Matty submitted a new will written by Ned, but there is a problem. Ned meets with Hardin, Matty, Roz, Heather and Lowenstein, who is handling the inquiry into Edmund’s death. Ned pretends that he re-wrote the will with Mary Ann, who is currently out of town, as a witness. Although the will is almost identical to the original document, Hardin points to an error that Ned made in the bequest to Heather. The error renders the will invalid and the entire inheritance is therefore bequeathed to Matty. Hardin also discovered that Ned ran into serious trouble when he made a similar error in the past. When Ned and Matty leave, Matty asks to see him that night. Meanwhile, Lowenstein and Oscar want to know how Ned got involved with Matty, but Ned insists that he updated the will before she showed any interest in dating him. Later, Matty reveals that she learned how to invalidate the will from a lawyer friend, but she never would have done it if she had known about Ned’s previous error. At the police station, Oscar questions Ned and discloses that Edmund’s glasses were not found at the scene, concluding that Edmund was murdered elsewhere and moved. Roz and Heather arrive to make a statement about the man Heather saw with Matty before the murder, but Ned deliberately greets them and Heather does not recognize him. Ned tells Matty about the glasses, and she supposes that the maid has them. Later, Lowenstein warns Ned that Oscar has come to suspect him, and cautions Ned that someone is setting him up. Ned learns from another lawyer that Matty was aware that Ned had previously written an invalid will, and Teddy informs him that Matty asked him for an additional bomb, which he instructed her to rig to a door. Soon, Matty calls Ned from Miami, reporting that she received Edmund’s money and sent it somewhere safe. Confessing that she paid off the maid to leave Edmund’s glasses in the boathouse, Matty asks Ned to retrieve them, but when Ned sees the boathouse door is rigged, he realizes Matty wants to kill him. Ned gets Edmund’s gun and waits for her at the gazebo while Oscar heads for the mansion to arrest Ned. When Matty arrives, she is surprised that Ned has a gun, and he claims there were no glasses in the boathouse. Oscar arrives as Matty heads to the boathouse to find the glasses. Ned drops the gun and runs after Matty, but the boathouse explodes. In jail, Ned realizes that Matty is still alive and that Mary Ann’s body was in the boathouse as a decoy. Dental records identified the body as Matty, but Ned theorizes that the woman he knew as Mary Ann was blackmailing Matty for stealing her identity, and Matty rigged the boathouse explosion to kill both Ned and Mary Ann. Later, Ned gets a copy of Matty’s high school yearbook and learns his theory was correct; the yearbook picture of Matty is the girl he knew as Mary Ann. The photograph of her classmate, Mary Ann Simpson, depicts the woman Ned knew as Matty. As Ned sits in his prison cell, “Matty” relaxes on an exotic beach.