Lucas helps a man after he's shot in a shootout by a man who wants to keep a secret about his past. When he allows Mark to take in a pet, he doesn't know that his decision will endanger his son's life.
A notorious gunfighter gets married and promises his new wife that he will take off his guns and begin a new life. However, a gang of outlaws who hear that he is in the area try to persuade him to break that promise and throw in with them.
A wagon train master forces a young couple to marry after they hide the fact that one is a girl, and Lucas takes them in to help them; but trouble soon arises when a drunken crowd calls for a Shivaree.
Lucas McCain and his son Mark come across U.S. Deputy Marshal Sam Buckhart who is escorting an Indian prisoner. To Lucas' surprise he finds that Buckhart himself is an Indian, educated at Harvard College. In North Fork, Buckhart goes about his business until some of the townsfolk realize he is an Indian and decide to take matters into their own hands. It's left to Lucas to show them the error of their ways.
As the second witness of a murder, Lucas is asked to travel to another town to testify at the accused man's trial. The catch is, the only other witness has been murdered and his killer has not been identified.
Lucas McCain is surprise when someone he once worked with, Sam Morley, shows up at the ranch. Lucas thought Morley had died but it turns out he's a wanted man and wants Lucas to do him a favor: turn him in for the $500 reward money that's available. Morley desperately needs the money so his girlfriend, Beth Landis, can get treatment for a serious disease. Lucas thinks he's on the level and decides to go along. Unfortunately another cowpoke who once worked with them, Hamp Ferris, rides into town and is looking to collect the bounty on Morley himself.
A corrupt marshal from outside North Fork goes after an outlaw with a price on his head. However, he sees an opportunity to make some extra money, so he murders an innocent man to pass off as the outlaw so he can collect the bounty, and then proceeds to blackmail the real outlaw.
Troublemaker Johnny Clover, a student at the North Fork school, wrecks the classroom one day. Lucas, a member of the town's school board, goes to Johnny's uncle to get him to pay for the damage, which turns out to be a task easier said than done.
Lucas McCain is none too pleased to see that Tom King is in town. King is a former lawman who always took 'dead or alive' to mean dead and acted accordingly. This time around, he's in town as a contract killer however having been hired to kill Oat Jackford, a bully of a man who many in town would love to see dead. King has a reputation that sends chills down most men's spines but Jackford's approach to dealing with if nothing if not unorthodox.
Lucas takes in an orphaned young boy, and one of the things he teaches the boy is how to use a gun. What Lucas doesn't know, however, is that the boy wants to learn how to use a gun so he can kill the banker he holds responsible for his father's death.
While walking down the main street in North Fork, John Hallager is shot from someone hiding in the shadows. Marshal Micah Torrance arrests Billy Mathis who had been seeing Hallager's daughter Lucy despite being told to stay away. Not long afterward, John Barrow McBride comes to town. He has a mind reading act that the townsfolk find entertaining but he also seems to have information about Hallager's shooting. How he got that information tells Lucas how McBride gets the information for his act but also leads him to the real shooter.
The three Malakie boys comes to town and bust up the saloon. Lucas McCain and Marshal Micah Torrance stop them, but in the course of doing so, one of the boys shoots and kills his own brother. That doesn't stop them from blaming Lucas however and when their father Daniel Malakie arrives, he breaks his two surviving sons out of jail intent on getting even. They ambush someone they think is Lucas but get it wrong and Lucas and Micah hunt them down.
Al Walker, a notorious gunfighter, has come to North Fork to die. He has an incurable illness and, since he had once been a wealthy and prominent lawyer, believes he owes it to his family to have his death certificate read "natural causes" instead of "killed in gunfight". However, the Porter brothers--a gang of vicious killers and bank robbers--have followed him to town and plan to take their revenge on Walker for killing their brother, and they'll stop at nothing and no one in order to do it.
Town ne'er-do-well Brett Conway finds out that a couple who moved near North Fork and soon fell sick are actually ill with highly contagious and potentially fatal yellow fever. Knowing that Lucas was the person who initially discovered the couple, Conway threatens to spread the news of their condition to the entire town, thereby causing a panic, unless Lucas buys his silence.
An outlaw gang kidnaps Micah and threatens to kill him unless their leader is released from jail. Lucas must decide whether to turn loose the notorious killer or face the possibility of the murder of his friend Micah.