Niní is an unemployed actress hired by two lawyers to pretend to be the daughter of a man of money. Lawyers try to blackmail him by inventing him an unrecognized daughter of a past affair. Without realizing it, Niní finishes in a boarding school of girls having to fulfill its role twenty-four hours to the day.
Along with "Divorce In Montevideo" and "Honeymoon In Rio", "Marriage In Buenos Aires" forms one of Manuel Romero's endearing trilogies. Entanglements, infidelities, and a happy ending.
Catita goes with her husband to spend the honeymoon in Rio de Janeiro and on the trip they fall into the hands of a player who will try to use them to achieve his ends.