In the Mexican-American quarter of a large West Coast city, matriarch Dona Maria Sandoval hosts a fiesta to unveil her design for a street that will showcase Latin American crafts and culture. The day's festivities are darkened by a rumor concerning the plans of American businessman J. J. Frentiss, who wants to build a warehouse on the land intended for Sandoval Lane. The next day, Dona Maria and her nieces, Elena and Loreto, visit J. J. at his office to implore him to change his mind, but the hard-hearted businessman proclaims Sandoval Lane an impractical dream and refuses to abandon his plans. After the women angrily leave his office, J. J. asks his nephew Phil for help in convincing the women to sell their property. Accepting his uncle's challenge, Phil ventures to Sandoval Street but is denied admittance to the house because he lacks a proper introduction. While pondering his alternatives, Phil rests at the wishing well outside the gates of the house and soon sees his old college friend, Tim O'Brien, pass by. When Tim tells Phil that he is now known as Tomas Obrion, the leader of a popular society orchestra, Phil threatens to expose his friend's true identity unless he introduces him to the Sandovals. Following Tim's advice, Phil assumes the name of Dolan and serenades Elena from the street. When the mischevious Loreto throws a rose to Phil, Dona Maria invites the serenader into the house and introduces him to Elena. As Elena and Phil stroll through the garden, Elena confides her dream of Sandoval Lane and her anger at the Frentiss family. Phil begins to court Elena, and when J. J. flies to New York on business, he orders his nephew to have the land deal completed by the time he returns. When Phil absentmindedly sketches a drawing of a building on a tablecloth, Elena guesses that he is an architect and insists on showing him the plans for Sandoval Lane. After Phil suggests several changes in the design, Elena hires him as the street's official architect and Dona Maria gives him the deed to her house as security for a bank loan. Meanwhile, in New York, J. J. is visited by several members of the Mexican Consulate, who have come to thank him for his commitment to Sandoval Lane. Furious, J. J. flies back to California and interrupts a fiesta in celebration of Sandoval Lane. When J. J. publicly reproaches his nephew, Phil admits that he is a Frentiss and is accused by Elena of betraying her family. The next day, Phil begs his uncle to return the Sandovals' deed. When J. J. refuses, Phil pleads for Elena's forebearance and then enlists his uncle' s secretary and butler in a plot to convince the old man that he is suffering a nervous breakdown. When J. J. receives a mysterious call from his attorney's secretary, arranging a meeting at the Sandoval house, the old man catches on to his nephew's plot but agrees to attend the meeting anyway. At the Sandoval house, Elena and the others entertain J. J. with an elaborate song and dance number to convince him to change his mind, and at the end of their performance, he announces that he has decided to move his warehouse to the other side of the railroad tracks.