He cannot make out what ails his pretty young wife, Mabel. She won't eat, won't be amused, won't do anything but sigh. Henry is uneasy about her. He writes to her Uncle John to come and help him discover the reason for his wife's discontent. Uncle John arrives and tells Henry he will find what the matter is. Henry hides behind the screen as Mabel enters and greets John affectionately. John tries to make her tell why she is unhappy. She finally discloses the reason, saying, "Henry isn't jealous." Henry nearly knocks the screen over, and it is only with difficulty that Uncle John keeps a straight face. John makes Mabel get him her husband's old soldier suit and dresses up in it, He says he has a plan to make Henry jealous, but it is to teach, not Henry, but Mabel, a lesson in jealousy. Henry pretends that he is furious when he sees from the street his wife sitting in the window with a soldier. He demands, when he enters the house, to know where the soldier is, Mabel will not answer. He storms about the room, finally taking down a saber from the wall and hastening out, saying, "I shall murder the destroyer of my home." The husband enlists the aid of his friends at the military club. They conspire to pretend that they are chasing him for having murdered one of their number. He daubs his saber with red paint and returns home. Mabel in scared so that she can hardly move when he shows her the red-painted saber. The soldiers force their way into the house. They overturn everything and follow Henry, who escapes out of the window, and down the street, brandishing their sabers. Mabel tries to keep up with them assisted by Uncle John. Henry is caught and Mabel is greatly surprised to see the soldiers shaking him by the hand and laughing uproariously. She smiles when told of the ruse and begs forgiveness. The soldiers "present sabers" as Henry takes her by both ears and kisses her. Thanks to Uncle John, she has had her lesson in jealousy.