Our first scene shows cowboys and their sweethearts, enjoying a quadrille on horseback. "Happy Jack" rides off with Belle Archer, the sweetheart of Jim. Jim, furiously angry, attacks Happy and the cowboys, taking Jim's pistol from him, hustle him out of the bunk-house. Later the pistol falls to the floor and explodes, the bullet striking and killing Happy, who is alone. The brave fellow writes on a piece of paper before he dies, "I shot myself accidentally, Jack." A gust of wind blows the note into a corner, Jim entering, is discovered examining his revolver over the dead man, and is accused of murder. Later, we see Jim on trial for his life. The lame cowboy finds the last message of Happy Jack. He limps out to the road and hands the paper to Jim's friend, the Pony Express rider. His horse goes lame. He lassos and mounts an unbroken broncho and is on his way again in a wild dash to save the life of his friend. The jury foreman is about to pronounce the verdict of "guilty," when the spunky rider dashes into the courtroom still mounted and delivers the message that proves Jim's innocence. Then a big hurrah for Jim and the Pony Express rider.