Based on Michel Houellebecq's controversial novel, this movie focuses on Michael and Bruno, two very different half-brothers and their disturbed sexuality. After a chaotic childhood with a hippie mother only caring for her affairs, Michael, a molecular biologist, is more interested in genes than women, while Bruno is obsessed with his sexual desires, but mostly finds his satisfaction with prostitutes. His pitiful life changes when he gets to know the experienced Christiane. In the meantime, Michael meets Annabelle, the love of his youth, again...
- The opening scene begins showing a computer screen with Michael (Christian Ulman) typing his decision to quit his job as head of the biotechnology institute in Berlin. He writes that it is a waste of his time and he would rather resume his research in Ireland involving artificial reproduction (a.k.a. cloning).
Michael and his co-workers celebrate his farewell with champagne. A group of male colleagues talk about work in the background and a woman colleague tells Michael of her admiration for him. In his office, Michael's boss expresses his appreciation and that he is proud of Michael for his work ethic and they also discuss Michael's reasons for leaving. After Michael is at home, he feeds his parakeet and opens a letter that says his grandmothers grave must be moved due to construction. As he reads the letter, his parakeet suddenly dies and Michael throws the birds body in the trash can under his kitchen sink.
Next we are introduced to Bruno (Moritz Bleibtreu), a high school teacher reading Baudelaire to his students. After he reads aloud he asks for comments. A girl in the front row gives feedback relating the literature to male fate. As the students and Bruno leave the classroom, he watches a girl buy condoms from a vending machine in the hallway. The girl who had commented on the text approaches him in the hallway and asks if he had corrected her paper. A flashback shows Bruno masturbating to her photo paper clipped to her essay. He tells the student that she has talent as a writer and that her essay was very good.
Michael lies on his couch and reminisces about a girl at a dance. He then hears music from a party in a neighboring building and he closes his balcony door. He gets an old box off the top shelf of his bookcase and reads letters and looks at photos from the same girl he was just thinking about.
Bruno smokes a cigarette while typing a vulgar and racist article on his typewriter. A baby cries and Bruno moves him to the other room. The baby continues to cry so Bruno crushes up half of a sleeping pill and puts it in the baby's bottle. Bruno meets with a man and wants him to publish the article Bruno had written. The man declines and tells Bruno he is talented, but a racist and a reactionary.
Bruno and Michael meet in a bar and we discover that the two are brothers. Michael tells Bruno about his parakeet and Bruno tells Michael about his wife and his negative feelings toward his life.
Bruno is again at work, in his classroom, this time alone with the student who asked about her essay. He sits in a chair next to her and puts his hand on her thigh. They stare at each other and she moves his hand away. He unzips his pants and tries to get her to touch him. She gathers her things and leaves the room. Bruno cries and hits the desk with anger. He drives to a mental health clinic and tells them that he cannot go home because he will kill himself. He has a session with a therapist and she asks him questions about his life. With every story he tells, we see a flashback of the event. He tells her that his mother was a hippie and left him with his grandparents. He is upset with his mother for not calling when Bruno's grandfather died. He tells the story of how his beloved grandmother died while cooking. He also briefly talks about his experience in boarding school. Lastly, he talks about a time that his mother took him on a vacation from boarding school to a hippie colony. There he was openly exposed to his mother's sexual experiences. He continues to tell the therapist about the vacation and how he went into his mother's room while she was sleeping, and he looked at her naked body. Then he masturbated on a balcony to the thought of his mother and a cat watched. Afterward, Bruno threw a stone at the cat, causing it to fall to its death off the balcony. After the vacation Bruno's mother introduced him to his half brother Michael. She leaves them alone to get to know each other. The boys are about 17 years old. They talk about the book A Brave New World, and Bruno also meets Annabelle, Michael's friend who he thought about earlier in the film. Both boys are distant from their mother as she says goodbye and again leaves them. Back in real time, the therapist asks Bruno about his first sexual relationship, and we see a flashback of it. The therapist says that it has been a long session and she tells Bruno to go and get some rest.
Michael goes to the cemetery and watches a man remove his grandmother's remains from her grave, although the man warned him not to watch. After the cemetery we see him walk up the driveway of a house and turn around. An older woman comes out and greets him. Mrs. Stevens brings him in the house and he greets her husband and son. Then Annabelle (Franka Potente) walks into the room. Michael agrees to stay for dinner and helps Annabelle set the table on the back patio. The two catch up on their lives and reminisce about their childhoods that they spent together. She asks why he never answered her letters and he tells her that he had just read them just a few days before his visit. The two sit together in a room alone looking and old pictures. She asks why he never kissed her back then, and asks if he would like to kiss her now. They kiss.
Michael visits Bruno in the mental hospital, and tells him that their mother is dying. They drive to he house that Jane, their mother, shares with other hippies. An old woman tells them which room Jane is in. She is lying in a bed in the middle of a room with lit pillar candles surrounding it. Bruno whispers angrily in her ear. A man brings Bruno and Michael two glasses and pours them each a drink. Michael walks around outside, leaving Bruno alone with their mother. Michael rushes back inside when he hears Bruno screaming a drunken song at his dying mother. As Michael arrives in the room, Jane takes her last breath.
Bruno smokes a cigarette outside and watches a pigeon on the roof. Michael joins him outside the hippie house and asks Bruno if he should take him back to the clinic but Bruno declines and says he is first going to a brothel.
Annabelle and Michael have dinner together and discuss Annabelle's past relationships. Annabelle reveals that she was pregnant at 19 and had an abortion. They sit down together in another room and she shows him her diary, in which she kept postcards Michael had sent her throughout the years, and she reads a letter that she wrote to an advice column about him. Annabelle asks about Michael's sex life, and he reveals that he is a virgin. They turn off the lights and make love, and she tells him that she has been in love with him since she was 5 years old.
Bruno and Michael meet in the same bar. Michael compliments Bruno on his new suit. Bruno tells Michael of his plans to go to a nudist camp, and that his wife, Anne, wants a divorce and has moved out with their baby boy. In the next scene Bruno knocks on a door and his father answers in a robe. He invites Bruno in, pours each of them a drink and lights a cigarette. His father tells of his failed career as a plastic surgeon and accidentally drops his cigarette in his glass of Vodka. The two chat for a few minutes. As Bruno gets up to leave, his father walks Bruno to the door and asks him if he could borrow some money.
Annabelle and Michael say goodbye at a train station and he promises to call her upon his arrival in Ireland. Next we see a car driving down a small road on the coast of Ireland. The car pulls into the parking lot of an office building, and a man escorts Michael down a hallway to another man's office. Michael and the man speak in English about his research and the man tells Michael that his calculations have been proven to be true. Michael is alone in a small house and he looks over his notes from his research a few years earlier.
Bruno drives through the entrance of the nudist camp and immediately sees a few topless women walking around. Bruno reads the directions for setting up his tent and a topless woman comes out from her tent to help. A nude man follows her out of the tent asking for her to come back in, as presumably their baby cries. Bruno declines her help. He wanders through tall grass and decides to relocate to an area with a few tents already in place, one of which has girls underwear hanging out to dry. At night Bruno sits outside his tent smoking a cigarette as he admires the young women in the neighboring tent. A truck pulls up playing loud music and the girls get in. Bruno is left alone and pours himself a glass of wine as the truck drives away and someone throws a can out of the bed of the truck. In the morning a woman is instructing a relaxation class, which Bruno is a part of. Bruno looks at a bulletin board with the schedule of classes offered. A man pours oil onto his arms and hands and he proceeds to massage a topless woman lying face-up on a table. Bruno watches from a distance. Men and women in swim attire approach each other in search of a massage partner. Bruno is left with another man and the two take the last open table in the circular arrangement of tables on grass near the water. Bruno pours oil on the man, who is now lying on the table, and observes the other male-female partners on the other tables. He walks away, frustrated. At night Bruno approaches a woman dancing alone outside a drum circle. He offers her a drink and they talk about the music and dancing. Another man walks up to her and her attention switches to him. Again Bruno walks away from the situation. He wanders through the dark trees and comes to a Jacuzzi, in which two people are engaging in intercourse. Bruno goes in anyway. The man gets out of the hot tub and Bruno approaches the woman, who is the same woman that instructed the relaxation course earlier, and they kiss. In the next scene Bruno is in the woman's trailer with her, and she pours them each a drink. She sits down on the couch next to him and they talk about their thoughts on men and women. The next scene jumps to daytime and Bruno and the woman, Christiane (Martina Gedeck), hold hands while walking and chatting through the camp.
Michael and his Irish colleague are in a pasture and visit cows that Michael's formula had allowed to be artificially reproduced. The two enter a room full of other scientists who applaud upon their entrance. Michael gives a brief speech about staying in Ireland to continue his research.
Bruno and Christiane sit in beach chairs next to the shore, and they talk about their lives. They hold hands and reveal that they want to spend more time together.
Annabelle waits in a doctors office alone until a doctor arrives to tell her that she has abnormal cells and that she must have an abortion. At the same time, Michael walks alone on a rocky cliff, suddenly stops, turns around, and runs back to his phone. He calls Annabelle and she hears the phone but doesn't answer.
Bruno pours wine into glasses set on a living room table. Christiane walks through the doorway in lingerie and asks Bruno if he would like to go out. They go to a swingers club, walk to the bar and socialize with another couple. Bruno and Christiane take a taxi home and they discuss living together and they tell each other, I love you.
Michael discusses his findings on reproduction with two colleagues and a third colleague comes in to inform Michael that he has a phone call from Germany. It is Annabelle's mother and she tells Michael about Annabelle's abortion and poor health. Michael goes to her immediately. Annabelle is sleeping in her bed when Michael arrives. He sits on the bed with her and holds her hand. She wakes up and smiles at him. The couple eats together on the patio. They sit on a wall together admiring her parents as she tells Michael about the love and loyalty her parents have for each other. Michael and Annabelle hold hands and lie together in bed and he promises to stay with her until she is well. He asks her to go to Ireland with him and she agrees.
Christiane looks at her skin in the mirror and notices some spots that have been reoccurring. Bruno walks in and is concerned. He fills up their wine glasses in the living room and Christiane again walks in wearing lingerie. The two go to the sex club again and are each with separate partners but they maintain eye contact with each other. Christiane makes a sound of pain and falls to the floor. Bruno waits in a hallway of a hospital and a doctor comes out of a patients room to tell Bruno that Christiane's legs are paralyzed due to the progression of a pre-existing medical condition. Bruno goes to Christiane's bedside and crying, he asks why she didn't tell him about it. Bruno waits outside the hospital for Christiane, who comes out in a wheelchair. They hug; he gives her flowers and asks her to move in with him. Christiane asks if he is sure, but Bruno cannot answer her question. The hospital attendant takes her home. Christiane sits at her home alone, staring out the window and at her paralyzed legs. She also glances at the telephone. Meanwhile, Bruno is lying on his floor with an empty pack of cigarettes and a bottle of vodka. He gets up, staring at the phone. He proceeds to call Christiane but hangs up after the first ring. Christiane drinks wine in her wheelchair and continues to stare out the window. Bruno tries to call her again, but he hangs up before she can answer. She wheels herself to her balcony and pulls herself up out of the wheelchair. Bruno calls again and lets the phone ring. Christiane hears the phone but instead of answering it, she pulls her legs up over the railing and throws herself off the balcony. As Christiane doesn't answer his calls, Bruno rushes to her apartment. When he arrives there is caution tape, two police cars and a crowd of people. He asks a bystander what had happened and the man tells him that a woman in a wheelchair had jumped from an apartment above. Bruno goes to the mental health clinic and we see him walk down a hallway crying. A nurse approaches him and he says that he is back. Bruno has his own room at the clinic. The nurse visits him and tells him to take his pills. She tries to leave but Bruno asks to go with her. She leaves him alone in the hallway for a few minutes and Bruno sees a woman in a wheelchair roll to the other end of the hallway, away from him. He calls after Christiane and she turns around and comes back over to him. Bruno gets on his knees and lays his head in her lap. The two seem to be talking and interacting, but two nurses open a door to the hallway and find him kneeling on the floor, crying alone. Some time later Bruno is alone in his clinic room and he hears a knock. Annabelle and Michael have come to visit Bruno and take him out for a while. Annabelle and Michael hold hands in the front seat and Bruno imagines holding Christiane's hand in the back seat. The three relax in beach chairs on the shore and Bruno thanks them for bringing him there. There is a fourth chair next to Bruno and he imagines Christiane sitting there. The film ends with Bruno gazing at his imagined Christiane with a half smile, as he tells Michael and Annabelle that he wants to stay, even after Michael and Annabelle move to Ireland.