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.
Pretending to be hardened convict, Hardie escapes from prison with a felon who stashed the proceeds from a stagecoach robbery before he was captured. The Wells Fargo detective hopes that his new partner will lead him to the hidden loot.
Hardie offers an old outlaw whom he sent to prison the opportunity to earn a parole and a reward if he will lead a posse into an outlaw stronghold and help rescue a United States senator from his kidnappers.
An outlaw gang abducts a pretty woman doctor to operate on one of their wounded confederates. Hardie and a deputy sheriff, whose wife needs her assistance during a difficult childbirth, desperately attempt to rescue the young woman.
During the land rush of 1889, Wells Fargo selected a spot for its first bank and relay station in Oklahoma and Jim Hardie was tasked with buying a fast horse with plenty of stamina to carry its rider to the designated spot and stake the company's claim. When the dust settles, another group has laid claim to the designated spot. Hardie is ordered to investigate when neither the rider nor horse can be found to determine what went wrong with the plan.
Sent to Madden to investigate problems Wells Fargo's stagecoaches are having in the vicinity, Hardie discovers the town is run by a ruthless businesswoman who opposes the townspeople's attempt to have an election, going so far as to murder her opponent for chairman of the town council. Using the town's newspaper, Hardie helps organize the citizenry to bring good government to the community.
While riding shotgun to protect a valuable gold shipment, Hardie and his stagecoach driver an interesting collection of passengers - including a U.S. Army officer being sent to Fort Laramie to stand trial for massacring a peaceful Indian village. Hardie's trip is far from uneventful - first the stagecoach is robbed by an outlaw gang and then passengers and criminals alike are attacked by Cheyenne Indians bent on avenging the murder of their families.
During an attempted hold-up, Hardie guns down a man who the outlaw leader claims was not a member of their gang. Hardie learns the man was an ex-convict who had gone straight after being released from prison and travels to the dead man's home town to learn what he was doing on the street at the time of the robbery.
Hardie rides into a small town to present a reward check to a man who helped prevent a stagecoach robbery. The fearful townspeople claim that they've never heard of the man and when the Wells Fargo detective investigates, he discovers the hero's grave.
Hardie's train is robbed and he is left without funds in a small town whose businessmen refuse to grant him credit. With the help of friendly old pickpocket, Hardie manages to alleviate his money problems and bring the thieves to justice.
Hardie is sent to investigate the murder of a Wells Fargo agent and finds that the sheriff suspect their new schoolteacher, an ex-convict, of perpetrating the crime. Although Hardie's testimony sent the man to prison many years earlier, the investigator is convinced that the murderer is one of the town's and other leading citizens.
A Wells Fargo manager has second thoughts about a stagecoach guard he recently hired despite the man's lack of references. He remembered that the new guard wore a belt buckle similar to those worn by a notorious family of Texas outlaws and fears that they may be plotting to rob a valuable shipment and asks Hardie to investigate the man's background.
Hardie investigates a robbery and the murder of a Wells Fargo express agent. His only lead is a young outlaw who was wounded during the crime. With the help of the local sheriff, Hardie pretends to be Jesse James and tricks the youthful criminal into taking him to the gang's hideout. Once inside, Hardie is aided by a wanted man who he rescued from two murderous bounty hunters.
While investigating the robbery of a Wells Fargo office, Hardie witnesses the murder of its agent from a bullet shot from the hotel across the street. Hardie's investigation quickly focuses on a number of suspects, including two Wells Fargo employees who have dark secrets they wish to keep hidden.