The Rifleman- The Angry Gun Season 1 Episode 12

While traveling back to North Fork on the stage after selling their herd, Lucas and Mark are sharing the stage with a Marshal and his prisoner Johnny Cotton. When they stop to water the horses, some of Cottons friends are lying in wait. Cotton steals the money Lucas got for the cattle and his rifle. He sends Mark on with the stage but tracks the robbers as best he can given that he doesnt have a horse or a weapon.