Craddock becomes annoyed when Bennett seems more interested in courting pretty Anna Dawson then he is on running to earth the murderous Cain gang. When Gabriel Courteau suggests a plan to set a trap for the outlaws by offering to buy rifles, Bennett is more than ready to put romance aside in order to put the crooks out of business permanently.
Clive Bennett drives off an attack by Paul Cain, the last remaining member of a gang of cutthroats, but murderous outlaw escapes. Even though Cain remains at large, Clive decides to go continue with his wedding to the pretty widow, Anna Dawson, with his father officiating at the ceremony. Cain manages to slip into Bordertown determined to avenge himself upon the Mountie for killing his outlaw brother.
The notorious Nebraska Lightning gang ride into Bordertown and take a special interest in Marshal Jack Braddock. Jack learns that someone using his name killed the gang's leader and the five remaining outlaws have journeyed north to avenge his death. Fortunately for Jack and Clive, famed American lawman Bat Masterson has come to Bordertown for reasons of his own and offers to lend a hand in the coming shootout.
Wendell McWherter buys one of Edison's generators so his bank can have electric power - and light - twenty-four hours a day. Soon other Bordertown businessmen want their buildings wired for light and it appears candles and oil lamps will soon be only an unpleasant memory. Clive is convinced that Edison's invention will reduce crime in their town, but Jack isn't show sure. When McWherter's bank is robbed in spite of his new precautions, Jack's fears appear to have come true.
Craddock agrees to escort a Metis half-breed wanted for stealing horses back to Canada to stand trial. He quickly takes a liking to the young man, but finds the trip to Bordertown too exciting for his liking as he must fend off the attempts of his prisoner's fiancée to free him and a spurned suitor to lynch him.
When a cowboy accidentally drives a herd of wild horses into Bordertown while on his way to Spokane, Jack suggests he auction the animals on the spot to save him a lengthy journey. Just as the sale begins, three men ride into town, claim the herd as their own and accuse the first cowpoke of being a horse thief. In the ensuing scuffle, one of the men is killed. Clive and Couteau must backtrack the herd to determine who is the true owner of the horses.
While tracking Jim McKay, a man wanted for bank robbery and murder in Montana, with Corporal Bennett and Marshal Craddock, Gabriel Couteau discovers that their quarry is his long-lost brother. In spite of his revulsion for the criminal acts his brother has committed, Couteau agrees to help him escape the lawmen who are hot on his trail.
Marshal Jack Craddock is forced to kill a down-on-his-luck farmer who attempted to improve his financial situation by robbing a stagecoach. The farmer's children refuse to accept Jack's explanation, nor do they see his offers of assistance as anything more than his attempts at assuaging his guilty conscience. Instead, the children determine to exact deadly revenge upon the lawman.
Jack is shot while escorting a pair of desperadoes to jail. When his horse returns to Bordertown with an empty saddle, Clive rushes to recapture his prisoners, but his gun misfires, temporarily blinding him. Before the outlaws can close in to administer the coup de grace, Clive is unexpectedly rescued by a pretty, red-haired woman who is handy both in the woods and with a gun.
Clive, Jack and Couteau discover a small band of Indians dead of disease. A Catholic priest who was attempting to minister to them fears influenza killed the families and when Marie tries to treat an sick Indian child in a field, the priest attempts to stir up trouble by insisting that Bordertown's doctor is threatening their lives with illness by insisting on keeping the young boy in her house. Meanwhile Jack and Clive discover evidence that the dead Indians were poisoned.
Peter Olsen states Gabriel Couteau murdered a stranger who rode onto his family's farm and his teenage son, Karl, claims to have been an eyewitness to the shooting. The Olsen's charges are enough to convince Jack to make an arrest, but Clive thinks the newcomers' story is too pat. When Karl's friend, Willie Haddon, discovers that Karl couldn't possibly have seen the shooting, Peter's accusation begins to unravel.
Marie and Clive find themselves in the middle of a deadly game of cat-and-mouse being played by Jack and Don Carlos. Years earlier, Jack killed Don Carlos' brother while serving as a Texas Ranger and the Mexican rancher murdered the marshal's wife and daughter in vengeance. Still not satisfied that the score has been settled, Don Carlos has journeyed to Bordertown and hired a noted gunslinger to kill Jack and complete his revenge.
Dr. Marie Dumont is having a bad day. First she learns that Bordertown's new unscrupulous lawyer owns half of her general store, then she discovers that her new partner is representing a woman who is suing her for malpractice when her husband died while in the pretty physician's care.
A Cree Indian arrives in Bordertown with documents that prove that the Canadian half of the settlement and all the land to the North actually belongs to the Cree nation by a treaty signed with the British government. A Canadian official arrives to sort out the matter and Bennett believes that the government agent will go to any steps, including forging documents, to prevent the town from being turned over to the Native Americans.
When a rancher dies suddenly, Marshal Craddock writes to his nearest relative, a novelist living in Boston, Massachusetts advising him to journey to Bordertown to look at the ranch before selling out to the powerful ranchers' association. Both Jack and the writer believe that the older man was actually murdered and when the ranch foreman is beaten and shots are fired at the new owner, the American lawman investigates a lengthy list of suspects.
Bennett and Craddock's argument over whether to use Bordertown's supply of fireworks to celebrate Dominion Day or the Fourth of July are suspended when an itinerant peddler assaults town lawyer Louis Gilbert. Marie Dumont learns that the salesman considers Gilbert a traitor to the failed revolution organized in Paris by the French Commune ten years earlier. Realizing that further bloodshed between the two men is inevitable, Jack and Clive arrange for a duel on American soil.
After killing a Mountie, the Connaught Gang send their newest member into Bordertown impersonating the dead lawman to gather information about a payroll shipment. The young man begins to have second thoughts about his career as a criminal when he discovers the respect the townspeople give to their red-coated lawmen.
Young Willie and Nancy's plans for a peaceful picnic are dashed when the youngsters discover the body of a murdered man on the river bank. The man turns out to be a bank robber who was being pursued by Lee Ford, a legendary American lawman. When the receipts from his latest robbery aren't found in the man's camp, Craddock and Ford suspect that the criminal was murdered and the money stolen by French scientist who was working nearby. Nancy and Willie try to convince Jack that his instincts about the Frenchman are wrong.
Clive's former partner in crime, Archie Stanton, travels to Bordertown after being released from prison in hopes that Clive can help him find honest work. Clive gets Archie a job working as a blacksmith for the town banker, McWherter, but when a large sum of money is stolen, the ex-convict is blamed. Clive is convinced that his friend was framed and with Jack's help, tries to find the real criminal.
An outlaw gang breaks into Marie Dumont's home and forces her to remove a bullet from a gang member's shoulder. While they wait for the injured man to recover from the operation, the criminals hold Marie and her young assistant, Lucy, hostage. When the men show no signs of leaving, Jack and Clive are forced to devise a desperate plan of rescue.
Joanna Radway hires two men to persuade an African-American farmer to sell his land to her because of the stream that flows through his property. When the thugs exceed their authority and physically abuse the man, a black gunslinger, and old friend of Jack's, intervenes, kills the men and steals the money Radway took from the bank to buy the land legitimately.
When one of Joanna Radway's cowboys becomes deathly ill after visiting Zack's saloon, the ranch woman blames the bartender and destroys his saloon with an ax. Marie suspects that Zack may have purchased some tainted whiskey and is abducted when she confronts his new distributors.
Willie Haddon and his father are traveling to Paris, France, to visit the home of his ancestors. Knowing an outlaw with a hankering for vengeance is lurking near Bordertown, Marshal Craddock decides to accompany the boy to the town where they'll meet their steamboat. Meanwhile, Corporal Bennett must deal with some railroad builders who are trying to break their companions out of jail.
Wendell's courtship of Sally Duffield hits a snag when his bank's home office orders him to foreclose on her boardinghouse's mortgage. While Jack tries to teach a callow youth the finer points of sparking a pretty girl, Wendell and Zack organize a Harvest Dance in hopes Bordertown's residents will pass the hat to pay off Sally's indebtedness.
A vicious storm forces Marie and her fellow stagecoach passengers to spend the night at a rundown stagecoach way station. During the night an assortment of unsavory men also seek shelter, some of whom are aware that the stationmaster keeps a large amount of cash hidden under the floorboards. Back in Bordertown, Sally, Clive and Jack must deal with a difficult childbirth without Marie's help.
An old enemy from Jack Craddock's days in the Texas Rangers journeys to Bordertown to avenge the long years he spent in prison because of the marshal's testimony. Jack is severely wounded by the old outlaw. While Marie tends to his wounds and Clive attempts to find help, the delirious lawman proposes to his pretty doctor.