The Das family is in India on vacation, and Mr. Das has hired Mr. Kapasi to drive them to visit the Sun Temple. The family sits in the car, which is stopped near a tea stall. Mr. and Mrs. Das are arguing about who should take their daughter, Tina, to the bathroom, and Mrs. Das ultimately takes her. Ronny, their son, darts out of the car to look at a goat. Mr. Das, who closely resembles Ronny, reprimands him but does nothing to stop him, even when he says he wants to give the goat a piece of gum. Mr. Das tells Bobby, the younger of their two sons, to go look after Ronny. When Bobby refuses, Mr. Das does nothing to enforce his order.
Mr. Das tells Mr. Kapasi that both he and his wife were born and raised in the United States. Mr. Das also reveals that their parents now live in India and that the Das family visits them every few years. Tina comes back to the car, clutching a doll with shorn hair. Mr. Das asks Tina where her mother is, using Mrs. Das’s first name, Mina. Mr. Kapasi notices that Mr. Das uses his wife’s first name, and he thinks it is an unusual way to speak to a child. While Mrs. Das buys some puffed rice from a nearby vendor, Mr. Das tells Mr. Kapasi that he is a middle-school teacher in New Brunswick, New Jersey. Mr. Kapasi reveals that he has been a tour guide for five years.
The group sets off. Tina plays with the locks in the back of the car, and Mrs. Das does not stop her. Mrs. Das sits in the car silently and eats her snack without offering any to anyone else. Along the road, they see monkeys, which Mr. Kapasi says are common in the area. Mr. Das has him stop the car so he can take a picture of a starving peasant. Mr. and Mrs. Das quarrel because Mr. Das has not gotten them a tour guide whose car has air-conditioning. Mr. Kapasi observes that Mr. and Mrs. Das are more like siblings to their children than parents.
Mr. Kapasi tells the Dases about his other job as an interpreter in a doctor’s office. Mrs. Das remarks that his job is romantic and asks him to tell her about some of his patients. However, Mr. Kapasi views his job as a failure. At one time, he had been a scholar of many languages, and now he remains fluent only in English. He took the interpreting job as a way to pay the medical bills when his eldest son contracted typhoid and died at age seven. He kept the job because the pay was better than his previous teaching job, but it reminds his wife of their son’s death. Mr. Kapasi’s marriage was arranged by his parents, and he and his wife have nothing in common. Mr. Kapasi, seduced by Mrs. Das’s description of his job as “romantic,” begins fantasizing about Mrs. Das.
When they stop for lunch, Mrs. Das insists that Mr. Kapasi sit with them. He does, and Mr. Das takes their picture together. Mrs. Das gets Mr. Kapasi’s address so that she can send him a copy of the picture, and Mr. Kapasi begins to daydream about how they will have a great correspondence that will, in a way, finally fulfill his dreams of being a diplomat between countries. He imagines the witty things he will write to her and how she will reveal the unhappiness of her marriage.
At the temple, Mrs. Das talks with Mr. Kapasi as they stare at friezes of women in erotic poses. Mr. Kapasi admires her legs and continues to dream about their letters. Dreading taking the Dases back to their hotel, he suggests that they go see a nearby monastery, and they agree. When they arrive, the place is swarming with monkeys. Mr. Kapasi tells the children and Mr. Das that the monkeys are not dangerous as long as they are not fed.
Mrs. Das stays in the car because her legs are tired. She sits in the front seat next to Mr. Kapasi and confesses to him that her younger son, Bobby, is the product of an affair she had eight years ago. She slept with a friend of Mr. Das’s who came to visit while she was a lonely housewife, and she has never told anyone about it. She tells Mr. Kapasi because he is an interpreter of maladies and she believes he can help her. Mr. Kapasi’s crush on her begins to evaporate. Mrs. Das reveals that she no longer loves her husband, whom she has known since she was a young child, and that she has destructive impulses toward her children and life. She asks Mr. Kapasi to suggest some remedy for her pain. Mr. Kapasi, insulted, asks her whether it isn’t really just guilt she feels. Mrs. Das gets out of the car and joins her family. As she walks, she drops a trail of puffed rice.
Meanwhile, the children and Mr. Das have been playing with the monkeys. When Mrs. Das rejoins them, Bobby is missing. They find him surrounded by monkeys that have become crazed from Mrs. Das’s puffed rice and are hitting Bobby on the legs with a stick he had given them. Mr. Das accidentally takes a picture in his nervousness, and Mrs. Das screams for Mr. Kapasi to do something. Mr. Kapasi chases off the monkeys and carries Bobby back to his family. Mrs. Das puts a bandage on Bobby’s knee. Then she reaches into her handbag to get a hairbrush to straighten his hair, and the paper with Mr. Kapasi’s address on it flutters away.