Bonanza - Season 8 Episode 11 : The Oath 1973

While in another town, on business, Ben runs into a saloon employee who is a big figure, and after he kills an old miner, who has burned down his house, Ben takes him into the sheriff. He is sentenced and hung. Before his departure, Charlie Monahan, has made his half-breed son, Charlie Two, swear an oath to kill Ben. Little Joe is made aware of this and must track him down to prevent him from carrying out his oath against Ben. Charlie Two is unaware that Joe is Ben's son, as they meet on the trail.