In 1988, wealthy New York investment banker Patrick Bateman’s life revolves around dining at trendy restaurants while keeping up appearances for his fiancée Evelyn and his circle of wealthy and shallow associates, most of whom he dislikes. Bateman describes the material accoutrements of his lifestyle, including his morning exercise, beautification routine, designer wardrobe and expensive furniture. He also discusses his music collection in scholarly detail.
Bateman and his associates flaunt their business cards in a display of vanity. Enraged by the superiority of his co-worker Paul Allen’s card, Bateman murders a homeless man and his dog. At a Christmas party, Bateman makes plans to have dinner with Allen, who mistakes Bateman for another coworker. Bateman gets Allen drunk and lures him back to his apartment. While playing “Hip to Be Square”, Bateman delivers a monologue to Allen about the artistic merits of the song, then murders Allen with a chrome axe. He disposes of the body, then stages Allen’s apartment so that others believe Allen has gone to London. Bateman is later interviewed about Allen’s disappearance by private detective Donald Kimball.
Bateman takes two prostitutes, who he names Christie and Sabrina, to his apartment and expounds on his opinions of the band Genesis. After they have sex, Bateman brings out instruments he uses for bodily harm. They later leave his apartment evidently bloodied and mistreated.
Bateman’s colleague Luis Carruthers reveals a new business card. Bateman tries to kill Luis in the restroom of an expensive restaurant, but Luis mistakes the attempt for a sexual advance and declares his love for Bateman, who flees in disgust. After murdering a model, Bateman invites his secretary Jean to dinner, suggesting she meet him at his apartment for drinks. When Jean arrives, unbeknownst to her, Bateman holds a nail gun to the back of her head while they chat. When he receives a message from Evelyn on his answering machine, he asks Jean to leave.
Kimball meets Bateman for lunch and tells him he is not under suspicion in Allen’s disappearance. Bateman invites Christie and his acquaintance Elizabeth to Allen’s apartment for sex, and kills Elizabeth during the act. Christie runs, discovering multiple female corpses as she searches for an exit. A naked Bateman chases her and drops a chainsaw on her as she flees down a staircase, killing her.
Bateman breaks off his engagement with Evelyn. That night, as he uses an ATM, he sees a cat, and the ATM displays the text “feed me a stray cat”. When he prepares to shoot the cat, a woman confronts him, so he shoots her. A police chase ensues but Bateman kills all four cops. Fleeing to his office, Bateman enters the wrong building, where he murders a security guard and a janitor. In an office he believes is his, Bateman calls his lawyer Harold Carnes and frantically leaves a confession regarding the many murders on Carnes’ answering machine.
Bateman then meets again with Detective Kimball, who remains suspicious of him but can’t prove that Allen was murdered, as Allen was spotted in London after the alleged murder took place, but the witness was unsure at first. Kimball tells Bateman that it’s possible Allen actually just went on vacation without informing anyone, leaving Bateman visibly disturbed.
The following morning, Bateman visits Allen’s apartment, expecting to clean up Allen’s remains, but it is vacant and for sale. He pretends to be a potential buyer but the realtor tricks Bateman into revealing that he isn’t there to buy the apartment. She then cryptically tells him that it isn’t Paul Allen’s apartment, before ordering him to leave. While Bateman goes to meet with his colleagues for lunch, a horrified Jean finds detailed drawings of murder and mutilation in Bateman’s office journal.
Bateman sees Carnes at the restaurant and mentions the phone message he left the prior evening. Carnes mistakes Bateman for another colleague and laughs off the phone confession as a joke. Bateman desperately explains who he is and again confesses the murders, but Carnes says that’s impossible, as he recently had dinner with Allen in London. A confused and exhausted Bateman returns to his friends, where they briefly muse on whether Ronald Reagan is a harmless old man or a hidden psychopath, before discussing their dinner reservations yet again. Left with the possibility that no one knows he’s a murderer, or that he simply hallucinated the various killings, Bateman’s voiceover narration reveals his realization that he will escape the punishment he desires, and that there has been no catharsis: “This confession has meant nothing.”