Jack Hargrave calls on his sweetheart, and as be takes from his pocket his engagement present, a letter falls to the floor unnoticed by him. Marion picks it up and insists upon reading it. That evening, when returning home, Jack mistakes a special officer for a burglar, and in the ensuing fight, Jack is arrested and taken to the station, where the letter, which contains a very queer proposition, is found, considered as incriminating evidence, and he is ordered into custody, to await his trial. During that period, he thinks of Marion, and she is summoned to testify, but she gives such testimony that Jack is sentenced to prison. Six months pass, and Jack has gained his liberty. He meets Marion and her fiancé, Lieut. Jones, U.S.A., on the street. She refuses to speak to him, and despondent, he enlists in the army. At the post, he is recognized by Jones, who subjects him to all kinds of indignities. One day, Marion and her mother arrive at the barracks for a visit, and the next day, Jones and Marion go for a picnic, taking Jack along in the capacity of a servant. Jack sees Indians and rushes back to warn the other two of their danger. Jones' yellow streak then comes to the surface, and he is about to desert Marion, but for Jack, who forces him to assist her. They ride furiously away, followed by the Indians. Arriving at the barracks, the colonel of the regiment, is told of Lieut. Jones' cowardice, and in his rage, strips the epaulets from him and orders him to his quarters. He then calls Jack and congratulates him. Marion recognizes him and asks his forgiveness, but love and trust once lost, never return, and Jack, giving a formal salute, goes his own way, leaving Marion to go hers.