The Narrator, often referred to as Jack, is an insomniac office drone who tries to find a way to connect with the world, and a girl named Marla Singer. He follows the words of Tyler Durden, a radical, Neo-Luddite who believes we are all slaves to consumerism.
The Narrator (Edward Norton), dubbed Jack for convenience, is suffering from insomnia at the beginning of Fight Club. He is living an empty-white collar life until he meets Tyler Durden (Brad Pitt). Tyler and him start a revolution on the consumer culture they both despise.
Jack, worried about his insomnia, attends a doctor. The doctor tells him to visit a support group for men with testicular cancer, to see real pain. Jack is initially uncomfortable at the group, until he is able to cry, but is able to after talking with another member Robert "Bob" Paulson (Meat Loaf). With the ability to cry, he can sleep. Jack becomes obsessed with the groups, and starts going to several, in order to cry. At one of his testicular cancer meetings, Marla Singer (Helena Bonham Carter) storms in. Marla is a tourist, just like Jack. Marla being at the meetings prevents Jack from crying, and prevents him from sleeping. He finally confronts her and divides the support groups between them. Jack can now go to support groups Marla-free, but it doesn't matter. He needs to go to more extreme lengths to connect with society.
On one of his numerous business trips, Jack meets soap salesman Tyler Durden. Tyler and Jack exchange some small-talk on their plane ride. Jack arrives to the airport to find that his suitcase has been thrown away, and also finds out his apartment has been destroyed. He attempts to call Marla, but can't collect the courage to ask her and opts to ask Tyler. Tyler and Jack share a beer and Tyler shares some of his thoughts with Jack. Jack isn't confident enough to ask Tyler for a place to stay, but Tyler realizes this and offers him a place to stay, in exchange for something. He wants Jack to hit him, and Jack reluctantly agrees.
He puches him, and Tyler reciprocates. Instead of feeling hurt, the two enjoy the feeling of getting hit and begin to have a fight. Tyler takes Jack back to his run-down home. They hold weekly fights in the parking lot of Lou's Tavern, with a crowd of men growing every week. They move the fights to the bar's cellar. Much like with the support groups, Jack finds therapy in the "fight club," until Marla reappears in his life. She begins to date Tyler, and she spends a lot of time at his house. The relationship is short-lived and once Marla leaves Jack's life again, he needs to find a new kind of "therapy."
Shortly after Marla leaves Tyler and Jack, they become more masochistic. Tyler uses lye, the crucial ingredient in soap, to burn Jack's hand. Then they take a step up from Fight Club with Project Mayhem. Project Mayhem is a full-blown war on consumer culture. They recruit members of Fight Club to cause terroristic acts around the city. Jack begins to feel rejected by Tyler, as he keeps many secrets from him and focuses most of his praise on a young Project Mayhem member Angel Face. Jack takes his envy to extreme measures and beats Angel Face severely at a Fight Club meeting. Jack gets into an argument with Tyler, just before they intentionally get into a car crash. Tyler leaves Jack, much Jack's father left him. Jack is left in the house, which now serves as the headquarters for Project Mayhem. He has a bitter confrontation with Marla, and then searches for Tyler.
Jack goes on a cross-country search for Tyler, encountering several branches of Fight Club along the way. The members act strangely towards Jack, even calling him "sir." One of the member tells him that he came to him yesterday, even though Jack doesn't remember that. In a frenzied state, Jack calls Marla to ask her if they ever had sex. In her frustration, Marla calls Jack "Tyler." Marla tells him that his name is Tyler Durden, and hangs up on him. Confused, Jack turns to see Tyler sitting in his hotel room. Tyler explains to Jack how they are the same person, that Tyler Durden is just a manifestation of what Jack wants to be.
Jack returns home to find out that Project Mayhem is planning on blowing up several credit card companies' buildings. Jack tries to stop this plan by going to the police, but the officers he is interviewed by turn out to be Project Mayhem members and try to cut off his balls. Jack escapes and tries to defuse the bomb in one of the building himself. Tyler appears, beats him, and takes him to the top of the building. Jack tries to reason with Tyler, but Tyler doesn't stop. The gun that was in Tyler's hand suddenly appears in Jack's hands. Jack shoots himself in order to kill Tyler. Tyler drops dead, and Jack is left seriously injured. Marla, captured by several Project Mayhem members, is taken to Jack. The members leave Marla and Jack alone, and Jack, finally able to commit to a woman, holds Marla's hand as the buildings that Project Mayhem planted bombs in, explode.
On the outside, Jack is cold, isolated and plain. Jack suppresses many of his radical, anti-consumer ideals. These ideals manifest themselves in Tyler Durden, his alter ego. Jack has issues committing to women, and expressing emotion. Before Tyler, Jack is very passive and non-confrontational. After meeting Tyler and forming Fight Club, Jack is able to confront people like his Boss (Zach Grenier) and Marla Singer. However, after Jack learns both the full extent of Project Mayhem and the fact that Tyler is his own split personality, he becomes regretful and tries to stop Tyler's plans from succeeding.