Gunsmoke S13E11 - Stranger in Town

Harvey Cagle, a resident of Dodge, owes money to someone in another town. He tries to convince the man he owes to give him time to pay him back, but the man gives him only a few weeks. While there he sees a gunfighter, named Dave Reeves, kills someone and decides to hire him to kill his partner Carl Anderson so that he could get control of the business they share. When Reeves arrives he finds out that the woman Anderson is seeing is his wife, who left him a few years ago, and this makes him want to kill Anderson more.