Miners have made a gold strike in western Montana, but the only men getting rich are the outlaws stealing it off Wells Fargo stagecoaches and freight wagons. Hardie goes undercover to the town of Aider Gulch to try to infiltrate the outlaw gang operating in the area and find out who is providing them inside information concerning gold shipments.
A man claims to have killed an outlaw who was wanted dead or alive. When he demands the reward Wells Fargo offered, Jim Hardie was ordered to Canada to identify the body since he was the only man alive who knew what he looked like. Hardie becomes suspicious when he learns the corpses face had been blown off by a shotgun blast. While he tries to learn more, the real criminal plots to kill the only man who can identify him.
The son of a dead man accused of robbing a Wells Fargo stage discovers an empty strong box in the attic of his farmhouse. The boy is still convinced that his father has been falsely accused and asks Jim Hardie to help find the real culprits.
A rich gold strike in Pleasant Valley has the Wells Fargo company scrambling to set up a new stagecoach run linking the boomtown with San Francisco. Hardie is detailed to find a trustworthy shotgun guard for the run and, of the objections of the branch manager, selects the son of a disgraced Wells Fargo employee to protect the gold dust and bullion being shipped.
Hardie picks up a valuable shipment in Matamoras, Mexico and isn't pleased when a dude and beautiful woman insist on becoming passengers on the stagecoach he will use to deliver the gold to a remote Texas town fighting Mexican bandits all the way.
Sam Bass and his gang have a hideout so secluded that no lawman has ever located it. From this stronghold they strike repeatedly, paying special attention to Wells Fargo shipments. Jim Hardie is ordered to infiltrate the gang so that he can learn where Bass's gang holes up between raids.
While transporting a prisoner, Dan Lingle, to stand trial for robbery and murder, Hardie's stagecoach is attacked by the outlaw's old gang. Among the passengers on the embattled coach are the Lingle's estranged wife and son and the outlaw determines to stand with them rather than to return to a life of crime.
When a Wells Fargo agent dies and fifteen thousand dollars is discovered missing from his office, the company orders and investigation. Jim Hardie isn't convinced the man died of natural causes and believes the money was stolen by whoever was responsible for his death. He gets a job in the local gambling hall to learn more about the man or men who could have been responsible for the crimes.
Hardie agrees to join the party searching for a young man who is seeking a lost gold mine in Arizona's Superstition Mountains. The men not only must deal with a lack of water, but the fact that the map the youth is following leads him into territory held sacred by the Apache Indians.
Hardie is in town to testify at the trial of a young man for armed robbery. The delinquent won't reveal the name of his partner because he's convinced that his confederate will make sure Hardie doesn't testify by scaring the Wells Fargo agent out of town. When Hardie refuses to run and then guns down the first outlaw sent to kill him, he discovers the criminal has hired notorious gunfighter John Wesley Hardin to finish the job.
Jim Hardie is sent to negotiate a right-of-way for their stagecoaches through Sam Brundage's property. Brundage's price - convincing Brundage's neighbor, John McCloud to share his water with the Brundages.
Hardie investigates a stagecoach holdup where white men posing as Indians killed the driver and the guard and left a pretty passenger for dead. Unlike the town's lawmen, who are convinced the robbery is the work of Billy the Kid and his men, but the woman who survived the attack convince Hardie otherwise.
At the annual auction of Wells Fargo's unclaimed luggage a man and a woman bid vigorously on a battered suitcase. Hardie wins the auction - until he is pistol whipped in an alley and the suitcase is stolen. Hardie suspects that the contents may lead him to loot hidden after a stagecoach robbery and is determined to retrieve the mysterious piece of luggage.
Jim Hardie is called in to when a stagecoach is robbed near the Arizona/New Mexico border. He discovers that the only thing that was taken was a yellow mongrel dog and, investigating further, learns that the dog's collar may provide evidence to prove that an accident in a gold mine was actually murder.
Reacting to a tip, Jim Hardie and his Wells Fargo agents set a trap for the notorious Stillwell gang, but the outlaws manage to outwit the detectives and escape with five thousand dollars. Now all the detectives can do is hope the marked bills appear so they can trace them to the outlaws who are passing them.
A valuable shipment of jade disappears on San Francisco's Barbary Coast, the City by the Bay's rough and tumble waterfront, and the Wells Fargo guard tasked with guarding the precious stones is found stabbed to death. The sea captain who delivered the jade is accused of murder, but Hardie suspects that an notorious criminal gang operating on the docks may have been responsible for the crimes.
When a train carrying a Wells Fargo express car is robbed, Hardie is assigned to recover the money that was stolen. His efforts are handicapped by a trigger-happy detective who disapproves of Jim's methods that include romancing the outlaw's pretty sister.
When a Wells Fargo express office is robbed of $10,000 and one of Jim Hardie's oldest friends, a witness to the crime, is murdered, the investigator is doubly intent on solving the crime. With the help of an aging sheriff and a spunky boy, Jim sets a trap to lure the criminals to expose themselves.