Ben Calhoun sells a herd of horses, uses the proceeds to get into a poker game, and wins the BPS&D railroad. He learns the railroad is broke but is determined to lay tracks to Scalplock while a disgruntled partner tries to stop him.
Calhoun's attempts s to acquire a right of way from a said to be merciless woman killer are complicated by the woman's demand for marriage as payment and the plans of a ruthless saloon owner to out maneuver him.
Calhoun's plans to obtain a right of way through the town of Paradise are jeopardized by four Confederate former comrades-in-arms he has hired. The men's rowdy behavior and total disregard for law has Tarrant advising they be fired, but Calhoun feels too obligated to the leader of the group.
Calhoun decides to go into the rugged Apache country hills for a fight to the death against Cougar Man, an Apache who has killed five of Calhoun's men, and who believes himself cursed to kill as many men as possible until he himself is killed.
Calhoun must transport an Army unit which has captured the renegade Sioux chief War Cloud and is bringing him to stand trial for numerous murders. This comes at a bad time for Calhoun, as he is hoping to impress another passenger, a wealthy banker whom he hopes will agree to a loan for the railroad. The banker's daughter believes War Cloud is being mistreated. But a man who lost his family in one of War Cloud's raids plans to make sure the Indian dies long before he arrives at the fort, and is willing to fight Calhoun to make sure of it.
Calhoun arrives in a small town to attend the wedding of an old friend. But he can find no trace of the man, and everyone in town just wants Calhoun to either leave or be killed, including the town boss, the father of the girl who was supposed to marry Calhoun's friend.
After Dave is captured and forced to work in a town of outlaw forced laborers, Calhoun decides to infiltrate it in the hopes of getting him out, though he might not get out himself if his cover is blown.
After a boiler on the train blows, Calhoun offers to refund all the passengers, but a headstrong woman is determined to continue on as planned to the mine her grandfather left to her. Rather than let her go alone, Dave accompanies her, but on the way they learn that others are just as determined to stop her from arriving in time to sign the deed---even though the mine does not have the gold or silver the grandfather thought it had.
Calhoun learns from Dave and Barnabas that all of the railroad's crew has been lured away by the promise of gold from a nearby mine. Actually, it is all part of a plot to lure Calhoun away in the hope of stealing the railroad.
After Calhoun rescues a headstrong young Indian woman from two buffalo hunters who were abusing her, he asks her to be his scout through dangerous terrain on his way to meet with a Sioux chief. She agrees, until she learns that he plans to negotiate putting the railroad through Sioux territory.
As Calhoun rides on the train with General Sherman on his tour, Dave, Barnabas, and the entire population of one of the train's stops are taken prisoner by a former Confederate officer and his group, who plan to assassinate the General.
After one of Breed Pembrooke's two sons is killed accidentally while robbing the train station, the ruthless man has Calhoun and the train conductor kidnapped and taken to his makeshift "town" where he finds them guilty of murder and sentences them to death. But he plans to submit the men to his sadistic games before killing them.
A cave-in traps Nils, another crewman, and a little boy in a tunnel. While Dave and others work to dig them out, Calhoun and Barnabas rush to retrieve a batch of nitro to free them. But their trip becomes more dangerous than ever when their wagon wheel collapses and they must seek the help of a preacher who believes they are damned, and someone else who is determined that they not make it back alive.
A man who sold lumber to Calhoun's railroad has disappeared, and his brother thus refuses to unload the lumber unless and until he is found to prove the sale was made. Suspecting two renegade Indians who quit just after the man left, Dave sets out to find them, along with the seller's brother. The behavior of the owner of a trading post leads them to suspect the answers are to be found there.
At a stop in town, Calhoun is forced to shoot a man. Unaware of who he is, two men then hire him to kill---Ben Calhoun. Calhoun decides to play along with the plot in the hope of discovering who is behind it.
While the train is stopped in the town of Banner, where Calhoun is making a major business deal with town founder Big Jim Banner, Barnabas is attacked by Banner's son, who thinks Barnabas is one of the Claiborne boys with whom the Banners have a major feud. At first it seems to be a mistake, until Barnabas meets Jeff Claiborne, who looks just like him. Soon Barnabas, who was raised as an orphan, starts to believe that he may be a Claiborne as well.
Six people from a stagecoach board Calhoun's train, all in fear for their lives after being followed for miles by a notorious gunman, who also boards the train. Calhoun puts him off, but he keeps following, and won't reveal which of the people he has been hired to kill, leading each of them to paranoid fear which may be a worse killer than his gun.
Calhoun finds an eight-year-old Arapaho boy alive as the only survivor of a battle with the Shoshone. He wants to bring him back to his people, but the Shoshone want him brought to them, as he is the son and heir to the slain Arapaho chief. Calhoun fears that he will be killed if brought to them, but local townspeople, including a close friend, want to maintain the peace with the Shoshone and thus do as they ask---while others in the town want to use the incident to start a new war.
With Calhoun away, the train is taken over by a group of ruthless outlaws who demand that Dave turn over a large fortune in bonds that is being delivered. Dave tells them that they will have to wait for Calhoun to return with them, but that is a delaying tactic as Calhoun will not be back that soon and Dave may have to resort to other plans to save the lives of the crew and passengers.
Calhoun is under orders from President Grant himself to safely transport Pierre Le Druc, an associate of Mexico's deposed puppet emperor Maximilian, to a meeting with his French countrymen on the west coast. But Le Druc is a ruthless killer, and a Mexican general is also pursuing the train to capture Le Druc and bring him back for trial.
When Calhoun's railroad is given the contract to haul for a mining company, it effectively puts the owner of the old coach freight line, who had the contract before, out of business. The freight company owner's inept sons decide to get back at Calhoun by robbing the railroad of the mining company payroll, and they hire a ruthless gunman to help them.
Calhoun wins a high stakes poker game against outlaw gambler Dan Patrick. But Patrick says he does not have the money on him, and offers a beautiful young Spanish noblewoman as collateral. Calhoun agrees to leave the young woman with Barnabas as he goes with Patrick to retrieve the money. But Patrick has no intention of keeping his end of the bargain.
Calhoun learns that he is transporting three female prisoners to Kansas City, and that one of them is the only witness against a ruthless mob boss being tried for murder. But the man has no intention of letting her arrive to testify against him, and has put his associates on the trail and on the train to make sure of it.