Through shifting narrative perspective, The Tortilla Curtain traces the intersecting lives of two couples living in Los Angeles, California. The first couple, Delaney and Kyra Mossbacher, are well-to-do white Americans living in the private community of Arroyo Blanco Estates; Delaney is a nature writer, Kyra a realtor. The second couple is Cándido and América Rincón, undocumented Mexican immigrants who are struggling to survive in a campsite at Topanga Canyon while they look for work in a new country. The novel restlessly bounces between the four protagonists’ perspectives, exploring the ways in which hatred and anger begin to affect each of the main characters in turn.
The novel opens with Delaney hitting Cándido with his car while driving on the canyon road. Though Cándido is severely injured, he refuses Delaney’s clumsy offer to drive him to a doctor, instead accepting the twenty dollars Delaney offers him and disappearing into the bushes. Waiting at the car dealership while his vehicle is inspected, Delaney calls his wife to inform her of the accident; he is careful to specify that the man he hit was “Mexican.” The next day, in Arroyo Blanco Estates, Delaney and Kyra’s dog is mauled by a coyote. Delaney attends a community meeting to speak on the issue of the local coyote population, but finds his neighbors wrapped up in a contentious discussion about installing a gate at the entrance to the community. Jack Jardine, Jack Cherrystone, and Jim Shirley are all in favor of the gate, but Delaney is wary as he sees gated communities as being in conflict with his liberal values. Overwhelmed by his more vocal neighbors, however, he does not offer his opinion.
Over the course of the next several days, Delaney and Kyra both go about their normal lives: Delaney continues working on his nature column, “Pilgrim at Topanga Creek,” and Kyra continues to devote countless hours to her work as a realtor, having recently become obsessed with one of her properties, the beautiful Da Ros home. While at the supermarket one day, Delaney has an encounter with Jack Jardine, who tries to convince him to support the gate. Delaney initially challenges Jack, calling him out for his racist views, but later, in the parking lot, seems to rethink his views when he spots Cándido, whom he instinctively thinks of as a “dark alien little man.”
The next day, still unsettled by his second encounter with Cándido, Delaney goes for a hike in Topanga Canyon and comes upon a man wearing a backwards baseball cap (José Navidad). Delaney is furious that this man and his friend are camping in the canyon, and heads back to his car with the intention of calling the police. However, he finds that his car has been stolen. Back at the car dealership, he can think only of Cándido’s face as he tries to imagine the person who stole his car.
Meanwhile, Cándido and América have been facing their own challenges in the canyon. Cándido managed to return to his campsite after the car accident and his pregnant wife, América, has been nursing him back to health. Much to Cándido’s chagrin, she has also been trying to find work at the labor exchange, though she has been unsuccessful. In the meantime, the Rincóns’ camp has been vandalized by Jack Jardine’s son, Jack Jr.; still injured, Cándido was able only to look on. Eventually, América finds employment working for Jim Shirley—though not before she has a disturbing interaction with José Navidad at the labor exchange, where he flirts with her aggressively and threatens that she won’t be a married woman for long. Returning from her first day of work in Shirley’s car, América is mortified when Shirley places his hand in her lap. She refuses to tell Cándido about the incident, instead focusing on celebrating her earnings. The following morning, América and Cándido both visit the labor exchange; América is again hired by Shirley, while Cándido finds work with Al Lopez, whose team is responsible for replacing Delaney and Kyra’s private fence (which they want heightened in order to prevent another coyote attack). That evening, América waits hours for Cándido to return to their meeting spot at the supermarket; when he does not, she heads into the canyon on her own. There, she is attacked by José Navidad and his unnamed friend. The two men brutally rape her on the canyon trail.
Part Two of the novel opens on Delaney, who has become increasingly resentful and angry following the theft of his car. After purchasing a new vehicle the same day his car is stolen from the canyon road, Delaney has lunch with Kyra, who leaves early to check on the Da Ros home. While making her rounds of the property, Kyra encounters José Navidad and his friend; frightened, she invents a lie about owning the house, claiming her husband and brother are inside. Meanwhile, Delaney, in the first throes of paranoia, has spent the afternoon camped out along the canyon road, waiting to see if someone will try to steal the new car he has just purchased.
Back in the canyon camp, Cándido can tell that something is wrong with his wife, but América refuses to tell him what it is. Since Navidad and his friend raped her, América has been experiencing terrible pain with urination (likely due to an STD). She refuses to share any of this with Cándido because she feels it will shame him. Despite América’s attempts to protect him, Cándido still feels emasculated by his wife’s assault and, one night, he beats her out of frustration.
The narration jumps ahead in time. The gate at Arroyo Blanco has long since been constructed, and Jack Jardine and company (including his sinister new friend, Dominick Flood, who is on house arrest) are now trying to convince Delaney that a wall should be built around the community, too. (Flood has already succeeded in having the labor exchange shut down.) One night, another coyote scales the fence surrounding the Mossbachers’ yard and makes off with their surviving dog in its mouth. Devastated, Kyra zealously begins to advocate for the wall, despite Delaney’s discomfort. Kyra only feels more frightened and angered when she finds that someone (presumably Navidad) has tagged the Da Ros house with the words “pinche puta” (fucking whore). Delaney also has another tense encounter with Navidad, whom he sees inside Arroyo Blanco handing out fliers.
Meanwhile, with the labor exchange closed, Cándido and América have set their hopes on finding work in Canoga Park, an urban subsection of LA. Instead, Cándido is beaten and robbed of all their money and he and América must both resort to eating out of a dumpster. Humiliated and hopeless, América refuses to return to the canyon, but Cándido drags her there. She becomes even more depressed and stops speaking. It is now November and Cándido is desperate to save money for an apartment before the rainy season begins; luckily, he finds work for a man named Señor Willis. While shopping at the supermarket on Thanksgiving Day, Cándido has another stroke of luck: two boys give him a turkey. In the canyon, as América prepares the bird, Cándido builds a fire. When the winds shift, a spark leaps from the flames and sets the whole canyon ablaze.
Part Three begins with Delaney and Kyra at a Thanksgiving Day cocktail party at Dominick Flood’s house. When news of the canyon fire reaches Arroyo Blanco, the residents, including the Mossbachers, flee to the hills. Here, Delaney again sees Navidad and his friend and tries to have them arrested, claiming they started the fire. When the Mossbachers return to their undamaged home (the fire has changed directions and ultimately been contained), Delaney discovers in a rage that Navidad and his companion have been released from police custody. In the chaos of the fire, Dominick Flood has also managed to escape his house arrest.
Cándido and América, meanwhile, have escaped the canyon fire but América goes into labor and must deliver her baby in a toolshed outside Arroyo Blanco’s walls. Cándido builds a new shelter in the hills with materials he pilfers from Arroyo Blanco homes, and he moves his family there. América soon discovers that her new daughter, Socorro, is blind, and she becomes desperate either to find the baby a doctor or to give up this difficult life and return to Mexico.
Several days after the fire, Delaney and Kyra are out searching for their cat, who is missing, when Jack Jardine picks them up and shows them that the wall has been vandalized. Delaney becomes obsessed with learning who the culprit is, and begins conducting nightly stakeouts of the wall. He develops a photo of Cándido scaling the wall, and becomes obsessed with punishing him. One day, he spots Cándido on the canyon road and tries to have him arrested; when this fails, he determines to track Cándido down himself. By the time Delaney discovers, later that evening, that it is actually Jack Jr. who has spray-painted the wall, he has thoroughly convinced himself that it is actually Cándido who is at fault—for the graffiti and for the fire—and that he deserves to be destroyed. Practically crazed at this point, a gun-toting Delaney hunts down Cándido and América’s shelter in the hills. Before anything can happen, however, a mudslide occurs and the canyon creek floods. In the flood, Socorro is drowned, though América and Cándido are fetched up alive on the roof of the post office. When Cándido sees Delaney drowning nearby, he reaches out a hand and takes hold of him.