Matt has a prisoner he is bringing back from Leavenworth to Dodge City. They are both on foot, presumably because the horses have died due to lack of water. The prisoner directs Matt to a watering hole which has dried up except or a small pool in the center of the river bed. Both drink from it, neither noticing the sign warning travelers that the water is poisonous.
Both become gravely ill and collapse. The prisoner rants about Matt having killed his brother and taunts him about the poisoned water giving him a slow death. They are saved when a cattle outfit headed for Dodge City discovers them and treats them.
During the ride back to Dodge City,
the prisoner recognizes an old acquaintance and offers him $3000 if he'll either set him loose or break him out of jail so he can kill Dillon. The man agrees only to break him out of jail.
When the drovers arrive in Dodge, Matt overlooks some of their boisterous behavior as a favor to his friend the trail boss. When they start shooting up the town and breaking into the stores, however, Matt insists on putting a stop to it. After a storekeeper shoots one of the men for falling through a window, his two partners are sent to jail.
Ross, the prisoner's acquaintance, encourages the drunken men to take a bucket of beer over to their jailed buddies. He uses this as a cover to release the prisoner. In the resulting shoot-out, the trail boss is killed.