Alejandro, a solitary, fragile and unpredictable man is crushed by the hostility of his mysterious past.

When a prominent researcher in the field of human memory returns home, he stumbles upon the fact that a man's past, as he remembers and tells it, is often nothing but fiction.

Gloria is a 58-year-old divorcée. Her children have all left home but she has no desire to spend her days and nights alone. Determined to defy old age and loneliness, she rushes headlong into a whirl of singles’ parties on the hunt for instant gratification – which only leads to repeated disappointment and enduring emptiness. But when Gloria meets Rodolfo, an ex-naval officer seven years her senior, she begins to imagine the possibility of a permanent relationship.

While house-sitting for a distant cousin, a lonely man fabricates the existence of a vindictive ex-wife withholding his daughter, in order to gain the sympathy of the single mother he has just met.

A man wants to become a TV-star and he will try anything despite his advanced age and what everyone says about him and his lack of talent and charisma for the job. But while he starts getting closer to his goal, his house starts crowding with unwanted guests.

Through illustrations and sounds, Una vez la noche experiments with the obsessive narration of four diverse characters –all of which are lost in the settings of their memory– to exhibit crucial events that marked their lives forever. Through a particular mise-en-scène, the film provides apparently ordinary people with a brilliant singularity, introducing us to a new perception of reality.

Chile, September 1986. Tamara, commander of the communist guerrilla group Manuel Rodríguez Patriotic Front, and her comrades-in-arms set out to overthrow the military regime installed in 1973 by assassinating the dictator Augusto Pinochet.

At a summit for Latin American presidents in Chile where the region's geopolitical strategies and alliances are in discussion, Argentine president Hernán Blanco endures political and family drama that will force him to face his own demons.

A pregnant woman, who is taking care of her son with development problems, is at her breaking point when a caregiver from the Philippines steps into her life. Diana suspects that she’s using voodoo against her after the quick improvements of her son.

Raquel is a teacher who resists the idea of retiring. One day she has to teach a class at her old school, only to find out she has been replaced with someone much younger. She insists still on teaching, and gets the support of her former students who will occupy the classroom demanding her reinstatement, leading to a small revolution that will threaten the establishment's order.