The movie is set in 1987, following a wealthy man named Patrick Bateman, who is engaged to a woman named Evelyn. He enjoys flaunting his wealth similarly to his coworkers-through his credit card. One fateful night, as he sees his associate named Allen showing of his business card, he is filled with jealousy. He is so jealous, in fact, that he kills a man and his dog. He also kills Allen, staging it to look like he ran from the country the moment he gets the chance to.
Bateman is interviewed by an officer about Allen’s disappearance. He then invites two prostitutes to his house, and they are later seen leaving his house covered in blood. His jealously is refueled when he goes back to work and sees the business card of another of his associates, Luis. He tries killing him, but his advances are looked upon as sexual lust by Jean, and Bateman flees. He kills a model instead in his rage and invites his secretary planning to kill her as well. However, their evening is disturbed by a message from his fiancé Evelyn.
The officer he spoke with earlier tells him that he is no longer a suspect for Allen’s disappearance. Using Allen’s house, Bateman invites two of his female acquaintances to his house, killing them both, right before he tells Evelyn that he wishes to stop their engagement. After he kills yet another woman, the police are after Bateman, though he manages to lose them by destroying their gas tanks.
Fleeing, Bateman enters an office that is later revealed to not be his, where he kills several people before leaving a confession for his lawyer. The next day, he expects Allen’s apartment to be the scene of a crime, yet instead it is cleaned and on sale. The realtor says it isn’t Allen’s apartment, and when Bateman goes to lunch with his coworkers, Jeans finds details of the murders in Batemans journal.
Meeting his lawyer, Bateman confesses everything again, yet the lawyer laughs it off as a joke, saying that he met Allen a few days ago. He understands that he will never be punished for his crimes and says that his confessions haven’t meant anything.