Jack Furth, a young civil engineer, and Jane Ross, a beautiful New York girl, are engaged. His employers send him to Mexico to inspect the mines of Jose Fernanz. He bids Jane good-bye, and upon arriving in Mexico he accepts the hospitality of Fernanz. Carmelita is the dark-eyed, impulsive and beautiful daughter of Fernanz. Manuel, a sprightly young Mexican, woos Carmelita, but she has been attracted by the engaging personality of Jack, and discourages the affections of Manuel. Carmelita loses her heart to Jack, but he does not reciprocate. He has thoughts only for Jane. Manuel becomes fiercely jealous, but Carmelita does not heed him. When Jack’s work in Mexico is finished, he returns to New York without a thought more than a friendly regard for the beautiful senorita. Jack marries Jane and they live happily. Life seems all sunshine and roses to them. When a lovely little baby came to their home, they thought their happiness was complete. Carmelita was inconsolable. Her spirit of unrest prompted her father to take her with him to New York on a business trip. There she meets Jack face to face. Her violent passion causes her to plot the death of her successful rival. She sends Jack a decoy telephone message, causing him to leave home for an hour. Seeing him leave the house, Carmelita obtains admission, and stealthily makes her way to the room occupied by mother and child. In the meantime, Jane had been startled by a cry from the child. Hurrying to its assistance, she found it in the throes of a violent attack of croup. Her inexperience renders her helpless to relieve it. Carmelita steals into the room and prepares to deal the blow, which will result fatally for Jane. In her anguish, Jane wheels about and observes her. Her only thought is tor the safety of her child. She appeals to Carmelita to save the baby. Then Carmelita is torn between two passions, one of vengeance, one to make Jack happy. Her better impulses win. and she seizes the child, directing Jane to hasten for a doctor. Their united efforts save the child. Jack returns home and is amazed at the explanation of Jane, who credits Carmelita with having saved the child. Carmelita returns to her Mexican home. Manuel again enters the lists, and is finally successful in winning her hand even if not her heart.