In San Francisco, California, a cocaine-addicted parking valet named Buddy Calamara greets Ray and Mickey Davis at an upscale restaurant, where they are celebrating their sixth wedding anniversary. As the couple goes inside, Buddy contacts his partner-in-crime, Scott Muller, by walkie-talkie. Scott breaks into the Davis house and steals artwork, a safe, and Mickey’s secret, erotic diaries, as well as an enlarged photograph of the young woman. Arriving home, Mickey is terrified by the loss of her journals, and fears the thief will discover her sexual fantasies. In the coming days, Scott engrosses himself in Mickey’s erotica and stages an “accidental” meeting with her outside a grocery store. Mickey is intrigued by the handsome stranger. She tries to seduce her husband at home, but Ray is preoccupied with finishing his latest children’s novel. Mickey returns to the store, hoping for another encounter with Scott. When they meet again, Mickey explains she is an interior designer and Scott claims he wants to remodel his apartment. She invites him to an event that showcases her work and Ray Davis becomes jealous of his wife’s new client. The next day at work, Mickey receives one dozen roses from Scott and an invitation to join him for lunch. At the San Francisco marina, Scott gives Mickey a $10,000 down payment for a $100,000 project. The next day, Mickey visits Scott’s loft to begin work. When she discovers a handgun, he teaches her how to shoot and they make love. Mickey returns home with a gun of her own and hides it inside her piano. Ray becomes incensed over their lack of intimacy, but Mickey blames her husband for being preoccupied with his book. Meanwhile, Scott and Buddy rob another mansion, but provoke the suspicion of a police officer. As the detective radios for backup, Buddy shoots him dead and the thieves get away in their van. Sometime later, Mickey meets Scott for lunch and is startled by his knowledge of her private life. However, he claims he read a magazine article about her. When Mickey tries to imagine Scott’s upbringing, he refuses to reveal his past, and she becomes fearful of their affair. She later admits she still loves her husband. As Scott drives away from the date, he is secretly followed by Ray and his literary agent, Marty Morrison. At a dockside warehouse, Ray sneaks onto the roof. As he looks down into the storage facility through an open ceiling fan, he sees the artwork stolen from his home and discovers Scott is the thief. At the same time, Buddy catches a glimpse of Ray. Since Ray is following Scott, Buddy realizes his partner-in-crime is having an affair with Ray’s wife. Still unaware of Buddy’s involvement with the robbery, Ray reports his findings to police. Elsewhere, at Mickey’s office, Scott begs her to leave town with him, and admits to reading her diaries. Scott declares he is worthy of her affection because he made her fantasies come true. Just then, Ray arrives and Mickey decides to stay with her husband. The next evening, the couple goes to the restaurant, unaware that Buddy is waiting for an opportunity to break into their home. At dinner, Mickey promises to talk openly about her sexual longings instead of keeping them in a secret journal. Meanwhile, Buddy heads to the Davis home and discovers that Scott is already inside, reading Mickey’s recent diary entries. The men hold each other at gunpoint as the couple returns home. Realizing there has been another break-in, Ray orders Mickey to telephone the police as he pursues the men with a fireplace poker. When a masked gunman appears at the top of the stairs, Mickey retrieves her weapon from its hiding place and threatens to kill the intruder, even though she presumes he is Scott. The man falls over, dead, but Mickey does not recall pulling the trigger. When police arrive, they unmask Buddy. At the same time, Mickey sneaks into her bedroom and finds Scott, wounded. As he admits to killing Buddy, the lovers exchange final glances and Scott climbs through the window to escape the police.