In 1968 Prague, Czechoslovakia, Tomas is a young brain surgeon and womanizer who views the political tensions under his country’s Soviet-influenced Communist government with amused detachment. After travelling to a spa town to perform a surgery, he attempts to seduce a charming waitress named Tereza but stops short when he learns that she lives with her mother. Although he says he might come back, Tereza does not believe him. Soon after, Tereza surprises Tomas by showing up at his apartment. He invites her in and instructs her to take off her clothes, a command he uses with all of his lovers. Tereza sneezes, saying she caught a cold on the train, and Tomas offers to examine her. While she initially resists his attempts to undress her, Tereza eventually succumbs to his seduction and kisses him. After they make love, Tomas wakes to find a sleeping Tereza clutching his hand. He receives a job offer in Geneva, Switzerland, that the chief surgeon at his hospital urges him to take, warning that a Soviet invasion is imminent. However, Tomas does not feel the need to leave. Allowing Tereza to stay at his apartment, Tomas continues his other dalliances, including an ongoing affair with Sabina, an artist whose defining detail, according to Tomas, is the black derby hat she inherited from her grandfather. After sleeping together one day, Tomas asks Sabina to help Tereza, who is an amateur photographer. Later, he introduces the two women at Sabina’s apartment, where Tereza takes notice of the derby hat. Back at Tomas’s apartment, Tereza wakes from a nightmare in which Tomas forced her to watch him make love to Sabina. After she recounts the dream, Tomas soothes her back to sleep. Tereza continues to take photographs on the streets of Prague, and her work is published in a magazine. She celebrates with Tomas, Sabine, and Tomas’s co-workers at a dancehall. Noticing a group of Communist government officials, Tomas calls them scoundrels. At the officials’ urging, the band plays a Communist anthem, prompting young dancers to boo and clear the floor. The chief surgeon and a young doctor, Jiri, discuss the atrocities committed by their government during its Stalinist period. Tomas suggests they did not know what they were doing and likens them to “King Oedipus,” who tore his eyes out once he realized he had killed his father and was sleeping with his own mother. The chief surgeon suggests Tomas write about the theory, but the younger doctor claims he does not care enough about politics. As Tereza dances with Jiri, Tomas becomes jealous. Back at their apartment, he admits he thought about Jiri being her lover, and Tereza is thrilled to have made him jealous. She tackles Tomas and asks him to marry her. Soon after, the couple weds in a small ceremony, with one of Tomas’s patients, Pavel, and Pavel’s pet pig acting as witnesses. Afterward, at a bar, a young woman sells puppies and Tereza insists they take one. Although it is a female, Tomas names the dog “Karenin” after “Anna Karenina’s” husband, since Tereza was reading Anna Karenina when they first met. As the chief surgeon suggested, Tomas writes an article comparing the Communist government to Oedipus and his friend agrees to publish it. One day, while swimming laps, Tereza has a vision of Tomas leering at naked women. He comes home late that night, and she begs him to involve her in his affairs. Tomas denies his infidelity but she says he cannot hide it. As she leaves the apartment in tears, he follows her and they both stop at the sight of Soviet tanks moving down the street. The next day, Tereza takes pictures of protestors who have swarmed the tanks. Passing by on her way to Switzerland, Sabina warns Tereza and Tomas to be careful. Tereza continues to take photographs as shots are fired at protestors. She gives a Dutch tourist her film, urging him to publish the photographs back in the Netherlands. Tomas tries to catch up with Tereza as a soldier points a gun at her and she points her camera back at him. Later, Tereza’s remaining photographs are seized and she is questioned in court. In Geneva, Switzerland, Sabina begins an affair with a married professor named Franz, whose political idealism clashes with her indifference. Sometime later, Tomas accepts the job in Geneva and moves there with Tereza and Karenin. Tereza tries to submit photographs of the recent Soviet invasion to a newspaper, but they reject them, claiming the story is old. Tomas rekindles his affair with Sabina, who tells him about Franz, saying she adores him although he dislikes her derby hat. When Tereza gets a call from one of the newspaper editors who believes she has a talent for nude photography, she seeks out Sabina as a model. At Sabina’s apartment, Tereza snaps numerous nude photographs of Tomas’s lover, then Sabina turns the camera around on her, commanding her to undress. As the women frolic around the apartment, Franz interrupts. Tereza runs to get dressed, and Franz informs Sabina that he has left his wife. She cries and embraces him. He promises to return the next day with the rest of his things and leaves. In the morning, however, Franz finds that Sabina has emptied the apartment and vanished. Tomas meets Sabina for a rendezvous at her hotel room. Later, Tereza tells him that life is too heavy for her, while it is light for him. She insists she has been weighing him down and says she is weak and will therefore return to Czechoslovakia, the country of the weak. On the train back to Prague, Tereza’s passport and camera are seized. Following her into the country, Tomas gives up his passport as well, and the couple reunites at their old apartment. Tomas returns to his former job, but the chief surgeon alerts him that he must sign a retraction, claiming he no longer believes what he wrote in his article about Oedipus and the Czech government. Soon after, a representative of the ministry of the interior comes to interview Tomas and produces another declaration for him to sign. Instead of acquiescing, Tomas quits and takes a job as a window washer. Working at a restaurant, Tereza meets an attractive engineer, who gives her his address as he leaves. After Tomas comes home smelling like another woman, Tereza goes to the engineer’s apartment but feels uncomfortable as he undresses her. She suspects someone is watching, but he denies it. After having sex with him, Tereza discusses the experience with another customer of hers, a former ambassador, who warns that the engineer may have been a government spy who filmed the interaction to blackmail her. Tomas finds Tereza crying by a river. She says she wants to leave, but he reminds her their passports are gone. The couple goes to a small village where Pavel, Tomas’s former patient, runs a farm. Living with Pavel, they embrace the country life and Karenin befriends Pavel’s pig. One day, they notice Karenin limping and soon discover the dog has cancer. Tormented by the news, Tereza suggests her love for Karenin is superior to her love for Tomas because she is not jealous of the animal. Tomas decides to end the dog’s pain, and on his way to retrieve a syringe, he discovers some of the nude photographs that Tereza took of Sabina. Before Tomas administers the injection, Tereza exclaims that Karenin is smiling. One day, Pavel’s nephew dislocates his shoulder and Tomas comes to his rescue. The patient ogles Tereza and says her beauty makes him want to dance. Tereza encourages everyone to go dancing, so they drive to a hotel, taking the pig with them. Since he is driving, Tomas rejects Pavel’s offer of a drink, but Pavel encourages him and Tereza to stay the night at the hotel. Sometime later, Sabina paints at a country home while a couple of American patrons observe her. She receives a letter from Pavel, stating that Tereza and Tomas have died in a car accident. On the night before their death, Teresa and Tomas flirt as they head upstairs to their hotel room. In the morning, as they drive home in the rain, Tereza kisses Tomas and asks him what he is thinking. He replies that he is thinking how happy he is.