Rodrigo Cataño seeks to impose in his family a Porfirian order. One day a door to door salesman, Roberto del Hierro, comes into the house to sell an American vacuum cleaner from the "Bright O'Home" company. Maru, Mr. Cataño's daughter, watches Roberto while he demostrates the new machine. Roberto leaves and says he will come back to explain Mr. Cataño about the vacuum cleaner. Mr. Cataño is very upset because a man has been in his house without him been present. Nevertheless, with fast and inteligent talk, Roberto sells him the vacuum cleaner and, later on, a refrigerator. Maru is captivated by Roberto and they fall in love. Mr. Cataño is furious when Roberto announces to him he will marry Maru.