A retired rock star, Johnny Boz, is stabbed to death with an ice pick during sex by a mysterious blonde woman at his apartment. Homicide detective Nick Curran investigates, and the only suspect is Catherine Tramell, Boz's bisexual girlfriend and a crime novelist who has written a novel that mirrors the crime. It is concluded that Catherine herself did it or someone who is trying to frame her out of spite. Tramell is uncooperative and taunting in the investigation, smoking in the interrogation room and exposing her bare genitalia in front of the officers. She presents alibis and passes a lie detector test. Nick discovers that Catherine has a habit of befriending murderers, including her girlfriend Roxy, who is later shown to have murdered several young boys on impulse, and Hazel Dobkins, who murdered her family.
Dan Gallagher (Michael Douglas) is a successful, happily married New York attorney living in Manhattan when he meets Alexandra "Alex" Forrest (Glenn Close), an editor for a publishing company, through business. While his wife, Beth (Anne Archer), and daughter, Ellen (Ellen Hamilton Latzen), are out of town for the weekend, he has an affair with Alex. Though he thought it was understood to be a simple fling, she begins clinging to him.
Dr. Bill Harford (Tom Cruise) and his wife, Alice (Nicole Kidman), are a young couple living in New York. They go to a Christmas party thrown by a wealthy patient, Victor Ziegler (Sydney Pollack). Bill meets an old friend from medical school, Nick Nightingale (Todd Field), who now plays piano professionally. While a Hungarian man named Sandor Szavost (Sky du Mont) tries to pick up Alice, two young models try to take Bill off for a tryst. He is interrupted by a call from his host upstairs, who had been having sex with Mandy (Julienne Davis), a young woman who has overdosed on a speedball. Mandy recovers with Bill's aid.
Edward (Richard Gere) and Connie Sumner (Diane Lane) are a married couple living in a suburban New York City with their eight-year-old son, Charlie (Erik Per Sullivan). Their relationship is loving but lacking intimacy due to their schedules.
Carly Norris (Sharon Stone) moves into an exclusive New York residential building, not long after the previous tenant, Naomi Singer, falls to her death from her balcony. She immediately crosses paths with other tenants including the handsome Zeke (William Baldwin).
New York City homicide detective Frank Keller is a burnt-out alcoholic. His wife left him and married one of his colleagues. He is depressed about reaching middle age and his 20th year on the police force.
A Miami area high school guidance counselor, Sam Lombardo (Dillon), is accused of rape by two female students, the wealthy and popular Kelly Van Ryan (Richards) and poor outcast Suzie Toller (Campbell), and hires lawyer Kenneth Bowden (Murray) to defend him. At trial, Suzie admits that she and Kelly had made everything up to get revenge on Lombardo: Suzie for him failing to bail her out of jail on a minor drug charge and Kelly for him having an affair with her mother, Sandra. Kelly's mother is humiliated by the scandal, and Lombardo and Bowden negotiate an $8.5 million settlement for defamation. In reality, however, Lombardo and the two girls were accomplices who used the trial as a way to get money from Kelly's wealthy family. To celebrate their success, the three of them have sex.
A young woman walking home from her birthday party is stalked by a man in distinctive sneakers. After she drops one of her presents, a police officer offers to escort her to her front door. The camera reveals that the policeman is wearing the same sneakers as the stalker.
Allison "Allie" Jones (Bridget Fonda) is a software designer in New York City, engaged to Sam Rawson (Steven Weber). In the middle of the night, Sam's ex-wife calls, and it is revealed that he slept with her recently. A hurt and angry Allie throws Sam out, breaking off their engagement, and is comforted by neighbor Graham Knox (Peter Friedman), an aspiring actor. The next morning she attends a business lunch with Mitchell Myerson (Stephen Tobolowsky), a fashion house owner who is looking to buy Allie's revolutionary new program. He manipulates her into significantly lowering the cost, on the basis that his recommendations within the industry will be her future business. As he is her first and only client, she accepts.
Set in London, the film opens with American best-selling author Catherine Tramell in a speeding car with her companion, Kevin Franks, a famous English football star. Tramell takes the man's hand and begins masturbating with it, all the while increasing her vehicle's speed. At the point of orgasm, Tramell veers off the road and crashes into the West India Docks in Canary Wharf. She attempts to save her partner but, as she says while being questioned by the police, "When it came down to it, I guess my life was more important to me than his".
Original Sin is set in the late 19th century Cuba during the Spanish rule, and flashes back and forth from the scene of a woman awaiting her execution by garrote while telling her story to a priest, to the actual events of that story.
Kate Miller (Angie Dickinson) is a sexually frustrated housewife who is in therapy with New York City psychiatrist Dr. Robert Elliott (Michael Caine). During an appointment, Kate attempts to seduce him, but Elliott rejects her advances.
During a particularly intense Florida heatwave, inept lawyer Ned Racine (William Hurt) begins an affair with Matty (Kathleen Turner), the wife of wealthy businessman Edmund Walker (Richard Crenna). They go to great lengths to keep their affair a secret, but Ned carelessly propositions an old school friend of Matty, Mary Ann Simpson (Kim Zimmer), thinking she was Matty. Matty soon makes it clear to Ned that she wants to leave Edmund but also wants his money, explaining that a divorce would leave her with very little due to their prenuptial agreement. Racine suggests the only option is to kill Edmund. While planning the murder, Ned consults one of his shadier clients, Teddy Lewis (Mickey Rourke), an expert on incendiary devices, who supplies him with a bomb.
High school teacher and writer Frannie Avery meets a student at a local bar, and when she heads to the bathroom sees a woman performing oral sex on a man. A few days later, Detective Giovanni Malloy questions her as he investigates the gruesome murder of a young woman, whose severed limb was found in her garden. They flirt despite the grisly nature of their introduction, and meet at the same bar later. Frannie is alternately thrilled and frightened by the detective's sexual aggressiveness, even as she grows more disillusioned with the attitudes and crude behavior of other men, including the detective's partner, Richard Rodriguez. Even as Malloy defends his partner, who can no longer carry a gun because he threatened his unfaithful wife, he promises he will do anything she wants except hit her. She leaves abruptly and is assaulted walking home, but calls Malloy and their affair begins that night.
Jennifer Haines (Rebecca De Mornay) is an up-and-coming Chicago attorney. She wins a big case, celebrates with the man in her life, Phil Garson (Stephen Lang), and returns to work to a hero's reception.