Bill is discharged from Bar K Ranch and in his desperation decide to turn train robber. On his way to town he rescues Myrtle Mulligan, who has been driven from protection to the high branches of a tree by a vicious bull. Arriving in town Bill applies to the superintendent of the railroad and secures a job as track walker. Pinto Joe, a friendly Indian, learns of Bill's train wrecking plans, and tells Myrtle about it. Hearing Bill intends to dynamite the bridge the plucky girl decides to take a hand in the game. Arriving on the scene just after Bill has lighted the fuse she fearlessly picks up the cartridge and throws it where it can do little damage. Rushing up the bank to the track she flags the oncoming train. When the passengers and trainmen cluster about her to learn the cause of the explosion she tells them that Bill saved their lives by finding the burning fuse just in time to prevent the blowing up of the bridge.