Gunsmoke S18E17 - Shadler

Just before he's to be hung, stage robber Shadler busts out of jail, by slugging his last rites priest and donning the robes as a disguise. While burglarizing an uninhabited farm, the escapee helps Deputy U.S. Marshal Newly elude hostile lawmen quarantining a nearby outpost struck by a mysterious plague. Newly believes his pursuers are actually a ring of vultures waiting to loot the dying settlement. When Newly heads back to the besieged town, the fake padre insists on riding with him to minister to the dying citizens. Why is the hardened Shadler risking his health and freedom to throw in with law enforcement?