The bandidos—Scarface and his associate, the state cop—come to Tres Camarones one hot day to deliver marijuana to a couple of American surfers. Immediately, Scarface and the state cop sneer at how provincial the town is. When they stop in at a taco shop, La Mano Caída, they harass both Tacho, the gay bartender, and Nayeli, a nineteen-year-old waitress. After the bandidos leave, Nayeli and Tacho go on about their day. Nayeli thinks about her father, Don Pepe, who's been in the United States for the last three years, and about Tía Irma's run for mayor. Nayeli even pulls out the last postcard her father sent, on which he wrote the phrase, "everything passes." In the afternoon, Nayeli's "notorious girlfriends," Yolo and the goth, Vampi, arrive to surf the internet on Tacho's computer.
The next day, the women of Tres Camarones travel to a lagoon to hunt for crabs. Nayeli finally admits to Yolo that when an American missionary named Matt came to Tres Camarones several years ago, she kissed him before he left. As the girls wade out of the water, Yolo is surprised to realize that nobody in town is pregnant. When she and Nayeli bring it up to the group, Irma and Tacho tell the girls that there are no men left in town to even get anyone pregnant—all of the men went north. The next day, when Irma takes the girlfriends to Mazatlán to shop, Irma tells Nayeli about her teenage love, Chava Chavarín. When Nayeli asks who will love her, Irma can’t answer.
As the election draws near, Irma bullies all the women of Tres Camarones into voting for her for mayor. She even goes to García-García, the owner of the local cinema, and bullies him into hiring a female projectionist—something he feels is wrong. Irma also forces him to agree to screen a Yul Brynner film festival, as Brynner is her favorite film star, and Irma believes he's Mexican. García-García agrees, and Irma wins her election by a landslide. García-García gets the films Westworld and The Magnificent Seven to show, and the entire village comes to the cinema for the festival. As Nayeli watches The Magnificent Seven, she feels tingly with excitement. After it's over, she leads Vampi and Yolo to the town square, where she tells them her plan: they need to go to the United States, find their own "magnificent seven" Mexican men, and bring them back to repopulate the village and save it from the bandidos. The girls agree and decide to take Tacho with them.
A few days later, Irma gathers the village in her living room. She mentions how when she won the Ladies' Bowling Championship in the 1960s in the United States, the Americans she encountered were kind and helpful. Irma gives Nayeli a phone number for her teenage love, Chava, and instructs Nayeli to call him when they get to Tijuana. Nayeli promises her mother that she'll try to bring Don Pepe back, and her mother encourages Nayeli to take Don Pepe's postcard. The village gives the girls money, and Irma drives them to Mazatlán to catch a bus to Tijuana. The bus driver, Chuy, promises Irma that he will care for the girls.
In the middle of the first night, Mexican police officers search the bus and pull off two Guatemalan immigrants, and the next day, Chuy stops the bus at a customs station. There, the Jefe (the customs officer) singles out Tacho and assaults him in the bathroom. The bus breaks down just outside of Mexicali, and the girls and Tacho end up catching another bus nine hours later. As they approach Tijuana, both Nayeli and Tacho think to themselves that the other side doesn't look as nice as it does in movies. When they finally arrive, they discover that their bags were never transferred from the first bus to the second, and nobody in Tijuana will help them. Tacho wonders if he's the only one who realizes how much trouble they're in. They go downtown to eat, and Nayeli tries to call Chava on a payphone. The operator insists that there hasn't been a number like the one Irma gave Nayeli since the 1960s.
Nayeli and her friends wander the streets of Tijuana until after dark. Finally, they stop at a taco stand, and a man asks Nayeli if she's lost. She admits that she is, and the man leads her to a motel in the red-light district. Though everyone is grateful and goes to sleep, Nayeli wakes up in the middle of the night to the man attempting to break into the room. Nayeli successfully uses her karate training to beat the man, but she doesn't sleep at all that night. In the morning, the group heads for the border wall and looks over to the other side. After watching the Border Patrol trucks, Nayeli leads everyone to the fruit market. There, two beggars, Doña Araceli and Don Porfirio, kindly invite Nayeli and her friends to come home with them. Nayeli is too tired to argue, and she allows the beggars to lead her to their home in the Tijuana dump. Nayeli is in awe of the poverty, filth, and how happy and kind her hosts are. In the morning, Nayeli wanders through the graveyards in the dump and thinks that the place is oddly comforting.
A young man, Atómiko, interrupts Nayeli's reverie and demands her attention. He holds a massive bamboo "samurai" staff, and he uses it to save her from meth-addicted "zombies" when they attempt to jump Nayeli. Atómiko follows Nayeli back to Porfirio and Araceli's home, where Yolo and Vampi decide that Atómiko is thrilling and interesting. He offers to get them over the border. When he whistles an obscene tune, an ancient Oldsmobile rumbles around the corner. The driver, a man named Wino, gives Nayeli and her group a tour of Tijuana before connecting them to a "coyote" who will smuggle them across the border. The coyote makes it very clear that he'll abandon his customers at the first sign of trouble. He ends up doing just that, though Nayeli and her friends realize the officer in question stopped to urinate, not to arrest them.
The group is soon stopped by officers and "taken in," but Atómiko succeeds in jumping back over the fence. Agent Anderson and Agent Smith take their "clients" to a holding pen. In the pen, Nayeli is separated from Tacho, so she studies the agents and tries to figure out what makes them different from her. A black agent named Arnie catches her eye, and he questions her. He finds her story entirely implausible but highly entertaining, so he buys her snacks. As the deportees are herded to a bus, Tacho yells the name of his bar (La Mano Caída), but an agent thinks Tacho said "Al Qaeda." They arrest him.
When Nayeli and her girlfriends find themselves back in Tijuana in the morning, Atómiko greets them and leads them to a motel. Nayeli sleeps all day and then calls Irma, who is can’t believe that Chava is no longer in Tijuana. Wino appears and offers to do Nayeli a favor. He drives them to a muffler shop outside of town, where his uncle shows them into an underground tunnel. When they get to the other side, another man receives them and drives them to a gravel lot outside of San Diego. Giddy with their success, Atómiko and Vampi swing on every swing set they see as the group wanders through the suburbs of San Diego. After they buy food at a Jack in the Box, Nayeli calls Matt, the missionary she kissed several years prior. Luckily for Nayeli, Matt is in town—though he's in town to bury his mother, Ma Johnston, who died suddenly a few weeks ago. He drives to get the girls and Atómiko and bring them back to his mother's house, and he marvels that the girls are women now.
The next morning, Matt takes the girls out for pancakes. At the restaurant, Vampi comes face to face with a Mexican man who is just as goth as she is, El Brujo. They go on their first date that night, and Vampi decides that El Brujo won her heart when he sings her favorite song to her. While they're out, Nayeli and Yolo look up Chava in the phone book and manage to track him down. Matt drives the girls to see him, and they discover that he's a janitor at a bowling alley. Chava tells Nayeli how he betrayed Irma by getting an American woman pregnant—though he never told anyone that the woman left him, and that he remained in the States because he was too ashamed to admit his mistake. This heartbreak turned Irma into "La Osa," the she-bear.
After beating and humiliating Tacho, the US officers finally send him back to Tijuana. Tacho goes to a gay bar, where a slightly older and evidently wealthy man, Rigoberto, takes an interest in him. Rigoberto invites Tacho back to his house, and Tacho gratefully accepts. The next morning, Rigoberto serves Tacho tea in a glass teapot, which entrances Tacho. Then, Rigoberto dresses Tacho up as his partner, Wilivaldo, and uses Wilivaldo's passport to smuggle Tacho over the border. The two men awkwardly say goodbye, and El Brujo picks Tacho up.
That night, Matt goes to his neighbor Carla's house, where he suggests they turn Nayeli into Border Patrol. Meanwhile, Chava joins the Mexican group for dinner and tells Nayeli that he knows a man named Angel who might be an appropriate "hero" to take back to the village.
The next morning, Chava takes Nayeli, Tacho, and Atómiko to a grocery store, where two white nationalists, Jimbo and Sully, harass them. Chava drives them the rest of the way to the migrant camp, where Angel appears out of the bamboo followed by none other than Jimbo and Sully. A violent fight breaks out, and Nayeli and Atómiko beat up the nationalists. When they get back to Matt's house after mindnight, Nayeli is shocked and hurt to discover that Yolo is having sex with Matt. Carla tells Nayeli that Irma called and is on her way, and Nayeli decides she must go to Kankakee, Illinois to find Don Pepe.
The next day, Nayeli encourages an extremely nervous Chava to see Irma. Matt helps Nayeli plan her trip, and Nayeli and Tacho leave in the morning. In San Diego, Irma accepts Chava with giggles and then conducts interviews for Mexican men. She interviews more than seventy men who want to go back, but she only agrees to take twenty-seven home with her.
As Nayeli and Tacho make their way to Illinois, they stop in Las Vegas. Although they are entranced by it at night, they find it disappointing in the daylight. Later in their journey, they stop at a Mexican restaurant in Utah, but when Nayeli admits that she and Tacho crossed the border illegally, the cook kicks them out. As they travel, several people mistake them for being Middle Eastern. Tacho grows more and more disillusioned, a feeling that culminates when he becomes extremely ill at the Mississippi River. He drives the last day to Kankakee with a fever, and Nayeli sets out alone to find Don Pepe. A man directs her to the library, where a kind librarian named Mary-Jo helps her track down her father and even drives Nayeli to Don Pepe's house. Once there, Nayeli is giddy with happiness until she sees her father get out of a truck with another woman and a toddler. Distraught, Nayeli leaves the postcard on his truck, and Mary-Jo helps Nayeli and Tacho buy bus tickets to return to San Diego. In Arizona, border patrol agents stop the bus. One of the agents turns out to be Arnie—the agent who bought her snacks when she was initially detained by Border Patrol. When he hears that their mission was successful, Arnie he drives Nayeli and Tacho all the way to San Diego instead of arresting them.
In the epilogue, Nayeli and Tacho are seen returning to Tres Camarones with Atómiko and an entire army of men, and the women of the village know that change has finally come.