Mexican teenagers Tenoch (Diego Luna) & Julio (Gael Bernal) are friends as close as brothers. When their girlfriends decamp to 'do Europe' for the summer, they decide to dedicate their time to the pursuit of sex & partying. At a wedding reception they cross paths with Luisa (Maribel Verdu) a young woman in her twenties but older than both boys. Immediately taken with her they invite her to take a roadtrip with them to an invented beach called ' Boca del Cielo' (Heaven's Mouth). Luisa declines but when a call from her husband confirms that he has been cheating on her, Luisa decides to take the boys up on their offer. As the trip is undertaken all three learn a lot about each other, not always happily, not always expected.