A single night tells the story of Lucía (Emilia Attias), a 36-year-old woman who has just separated from her partner, and on a failed trip to New York she meets Horacio (Naim Sibara), a man who seems to have lived all his life. in order. These strangers will spend the last night of the year together and during the evening, they will reach an agreement in which both of them must open their hearts with the truth without any lies.