The Basic Instinct Ending Explained: Who Was The Real Killer All Along?

The 1992 thriller "Basic Instinct" is full of twists and diversions, particularly for San Francisco Police Department Detective Nick Curran (Michael Douglas). Curran is assigned to investigate the murder of '60s rock star Johnny Boz (Bill Cable), who is stabbed with an ice pick while in bed with an anonymous blonde woman. 

Johnny's novelist girlfriend, Catherine Trammel (Sharon Stone), quickly becomes the prime suspect. Her latest book has a plot identical to the circumstances of Johnny's killing, and the similarities lead Nick and police psychologist Dr. Beth Garner (Jeanne Tripplehorn) to believe that either Catherine is the killer or she is being framed by a dangerous sociopath. 

Catherine has dual degrees in psychology and literature, and she combines her knowledge of the inner workings of the mind with her powerful charisma and a careful lifelong study of relationships and human behavior to build her power and influence over others. 

Throughout her questioning, Catherine seems to be two steps ahead of the police, playing constant mind games with Nick and the rest of the SFPD investigators. Catherine draws Nick into an affair and also generates enough paranoia in him that he begins to suspect that Beth is involved in the film's growing trail of murders.

Two of those murder victims are cops with ties to Nick. One is an Internal Affairs investigator named Martin Nilsen (Daniel von Bargen), who has recommended that Nick be fired. The other is Nick's partner Gus (George Dzunda), who is stabbed with an ice pick identical to the one used to kill Johnny Boz.

Nick discovers Gus' dead body in an elevator, and when Beth arrives on the scene and reaches into her pocket, he shoots her dead, mistakenly believing she is pulling out a gun. 

Investigators find evidence in Beth's apartment linking her to Johnny's murder and several other crimes, as well as pointing to an obsession with Catherine stemming from a college romance between the two women. Nick then goes to Catherine's home, where the couple makes plans for a life of peaceful domesticity together before having sex. 

Ominous music plays as the camera then pulls back to reveal an ice pick under Catherine's bed, revealing her to be the killer and the mastermind behind Beth's clever framing. While the implication is clearly meant to be that Catherine was behind Johnny and Gus' murders, the ice pick used in their killings had a wooden handle and the one shown under her bed is made entirely of metal, leaving some room for doubt to linger in the minds of filmgoers as the credits roll.

In 1992, Sharon Stone told Playboy that she was willing to entertain debate as to whether or not Catherine was responsible for the film's many murders.

"The thing about the character is that a lot of people don't know whether or not she was a killer," Stone said. "A lot of people really don't want her to have done it. It says more about them than about me. I think the role of Catherine met a certain need in society at a certain moment, and it ignited something. In her, everyone saw some person or some fantasy or some monster in their life or in their psyche."

Stone admitted that after bringing Catherine to life, the character remained with her when she fell asleep at night. "I certainly had nightmares," she said. "The kind of dreams that shake your core because you're pushing ethical boundaries. Once you break those boundaries — once you go beyond them without any kind of moral judgment — it has to affect your psyche." 

Unable to flush the character from her subconscious mind, Stone took Catherine to England in the 2006 sequel, "Basic Instinct 2." The sequel was nowhere near as well received as the original, earning a putrid 6% rating from critics at Rotten Tomatoes.