After a quarrel with her boyfriend on New Year's Eve, Mane (Pinal) drives her car from Mexico City to Cuernavaca to meet her parents in their country house. The car breaks down in the highway and Mane has to ask for help. Mechanic Cruci (Infante) arrives and, after testing the car, offers Mane a ride on his motorcycle. Back in Mane's house, she invites him some drinks to celebrate New Year's Eve. They get drunk and, the morning after, Mane's parents arrive and find them sleeping together. Not knowing what happened, Mane and Cruci are forced to get married against their will.