Tenoch Iturbide (DIEGO LUNA) and Julio Zapata (GAEL GARCÍA BERNAL) are best friends despite their familial differences. While Tenoch comes from a privileged background and famous family, Julio has not. Nevertheless, the two enjoy each other's company and imagine they're going to have some wild times now that their girlfriends, Ana Morelos (ANA LÓPEZ MERCADO) and Cecilia Huerta (MARÍA AURA), are traveling abroad.
Goofing off and spending time doing drugs with their friend Diego "Saba" Madero (ANDRÉS ALMEIDA), the two spot Luisa Cortés (MARIBEL VERDÚ) at a wedding. Married to Tenoch's cousin,
Alejandro "Jano" Montes de Oca (JUAN CARLOS REMOLINA), Luisa enjoys the attention the young men pay to her and their invitation to join them in traveling to a beach, "Heaven's Mouth," that they've made up.
She has no intention of doing that until Jano drunkenly calls her one night, informing her that he's had an affair. Distraught at this news, Luisa decides she'll join Julio and Tenoch on their trip. The two are excited about this, and once they get directions from Saba about where to go, the three head off on an extended road trip.
During that, the three learn things about each other, while Luisa decides to sow her wild oats with both men. That, and several unexpected revelations lead to turmoil and dissent in the group. As they continue on their trip and eventually run into Jesús "Chuy" Carranza (SILVERIO PALACIOS) and his wife, Mabel Juárez (MAIRA SÉRBULO) and their family, the three try to sort out their relationships with each other.