Roberto is depressed after his wife, Lucía, dies in a road accident. He decides to leave Puerto Vallarta and move to Mexico City with his 17-year-old daughter, Alejandra. Settling into her new school, Alejandra goes to a party one night with her classmates. At the party, she has sex with José, who films the encounter on his phone. The next day the footage has been circulated around the school, with Alejandra getting text messages calling her a slut. This provides an excuse for fellow students to bully and sexually harass her. She does not speak of these incidents to anyone.
The school organises a trip to Veracruz which all students must attend. At the resort, each room is shared by groups of four. Alejandra is bullied again into going into the shower by her female roommates. They then block the door of the bathroom. At night, while the rest of the students enjoy a party in the main room, the boys take turns to enter the bathroom and rape her.
The students then go to the beach to continue the party. When it ends, Alejandra is asleep on the beach as one of the boys urinates on her. One of the female students suggests she should go into the sea to wash herself. The rest join her and they have fun in the water. Alejandra disappears and the rest become anxious about repercussions. The next morning, the teachers discover she is missing and alert her father. He finds out about the bullying and is frustrated when the police cannot take action, as the crimes have been committed by minors.
Unbeknown to everyone, Alejandra is safe in a building where she went to sleep. Meanwhile, her father follows a car driven by José's father and kidnaps José after his father went to park his car. He ties Jose's hands behind his back and gags him. He drives to the coast where he hires a boat and takes José out to sea where he throws him overboard, before starting the engine again and continuing to ride in the sea.
^Young, James (20 September 2012). "'Mexico picks 'Lucia' for Oscar". Variety. Reed Business Information. Archived from the original on 25 September 2012. Retrieved 20 September 2012.
