Seventeen-year-old Colombian girl Maria Álvarez works in sweatshop-like conditions at a flower plantation. Her income helps support her family, including an unemployed sister who is a single mother, but after unjust treatment from her boss, she quits her job de-thorning roses, despite her family's vehement disapproval. Shortly thereafter, Maria discovers she is pregnant by her boyfriend, and he suggests marriage, but she declines because she does not feel she loves him, or that he loves her. On her way to Bogotá to find a new job, she is offered a position as a drug mule. Desperate, she accepts the risky offer, and swallows 62 wrapped pellets of drugs, and flies to New York City with her friend Blanca, who has also been recruited as a drug mule. Maria is almost caught by U.S. customs who are suspicious after finding Maria's $800 in cash and wanting to make a surprise visit to a sister she "hasn't seen in years", but not knowing anywhere else to go if she isn't home. She tells them that the father of her child paid for her plane ticket. She avoids being X-rayed due to her pregnancy, and is released. The traffickers collect Maria, Blanca, and Lucy, another more experienced mule that Maria had befriended during her recruitment. The mules are held in a motel room until they pass all the drug pellets. Lucy falls ill when a drug pellet apparently ruptures inside her. Unknown to the traffickers, Maria witnesses them carrying Lucy out of the hotel room, and she sees blood stains in the bathtub. She comes to the conclusion that the traffickers cut her open to retrieve the other drug pellets inside her body. Scared, Maria convinces Blanca to escape with her while the traffickers are gone. They leave with the drugs they have passed. Maria has nowhere to sleep, and goes to Lucy's sister's house, but doesn't reveal to the sister that Lucy is dead. Blanca soon joins her there. Eventually the sister unexpectedly hears of their involvement in her sister's death and throws them out. Blanca and Maria make an agreement to return the drugs to the traffickers and receive their money. Maria uses some of her drug money to send Lucy's body home to Colombia for a proper burial. Maria and Blanca are ready to board the plane back to Colombia when Maria decides to stay in the United States. Blanca returns home without Maria.
The film was critically acclaimed. It garnered a 97% approval rating on the aggregator site Rotten Tomatoes, based on 144 reviews, and an average rating of 8.02/10. On Metacritic, the film has a weighted average score of 87 out of 100, based on 39 critics, indicating "universal acclaim". According to Desson Thomson from The Washington Post, "Catalina Sandino Moreno is a Colombian Mona Lisa, a delicate, unforgettable force majeure. Add to her luminous demeanor a story that rips fleshy holes through your heart and you've got yourself a stunner of a film". Writing for Rolling Stone, Peter Travers gave the film 3 out of 4 stars, praising Moreno's performance, the screenplay, and Maston's direction, saying: "Remember the name Catalina Sandino Moreno. The heartfelt and harrowing performance she gives here should put her in line for a heap of year-end awards." The film was nominated to the Golden Bear at the 54th Berlin Film Festival.