Mourners offer Eva their condolences at Toole’s funeral. Eulogizing, Mickey notes how much Toole loved his wife. On the other side of town, Ruth baptizes Sean in the river and laughs as they fall in the water. When Sean aggressively kisses her, Ruth rebuffs him and leaves him standing alone in the water.
In the railway office, Durant reads a telegram informing him that the military won’t send reinforcements without better intelligence on the Sioux. Cullen angrily crumples up the letter as Durant cautions against panicking “every time someone sees an Indian.”
Elam enters Lily’s train car and reveals that Durant has hired him to kill her in exchange for his house by the river. When Elam asks if she has any reason that would stop him, Lily pulls out a gun. But she lays it on the table, explaining that the Durants will be arrested once the ledger reaches authorities. Lily offers Elam the Chief of Security position once she and Cullen replace the Durants. They shake on it.
The next day, a horse trots into town with a body slung across its back: It’s The Swede, unconscious and badly burned.
Lily confronts Durant about Elam. “I won’t be pushed out,” she declares, listing the trials she’s endured for the railroad: “I even endured your bed.” When Durant calls her a whore, she retorts, “Know then, that when your precious railroad is ripped from your thick and grasping fingers, that you’ve been undone by a whore.” Durant panics, asking what she’s done.
As a nurse tends to his wounds, The Swede tells Hannah that the Sioux turned on him and he regrets betraying the town. The Swede warns that the Sioux will attack the next day, and Cullen fetches a guard to keep watch over him.
Durant anxiously searches the safe and discovers his ledger is gone.
In the street, Lily restrains Cullen after she tells him of Durant’s plan to kill her. The ledger has already been mailed and she will need Cullen’s help convincing the board to take Durant down.
Cullen recruits Elam’s help fighting the Sioux. “Thanks for not killing my lady friend,” he adds.
Durant visits the semi-conscious Swede and asks how damning the ledger is. “You’re suffering, that is good,” The Swede wheezes. “Suffering builds character and you will need that during your incarceration.” Durant storms out in anger.
Flashing forward to after the town’s destruction, an interrogator informs Cullen that Durant is in custody.
Back before the destruction, Sean brings Ruth her travel bag as women and children prepare to evacuate. Incredulous, Ruth insists her place is in town with the church. When Sean reveals he’s arranged for them to be married in Council Bluffs the next day, she again rejects him, saying, “I’ve already given you my answer.”
As Elam and Psalms inspect a shipment of weapons, Elam notices that Eva did not board the train. She says she will hide in Elam’s house and expresses remorse over her role in Toole’s death. Elam insists she’s not to blame: “He took the coward’s way out.”
The Swede escapes his handcuffs and slits his guard’s throat.
That night, the Sioux attack. Cullen, Elam and the townsmen fire at the Indians as they stream into town.
Durant protects Hannah in the railway office as Indians raid the buildings, setting them on fire. Elam and Lily protect the whorehouse, and he sees the Durants flee the besieged railway office.
Eva cowers in Elam’s house as fire-arrows hit the wall. Elam rescues her and they run as the house goes up in flames.
As Hell on Wheels burns, The Swede dances in the street.
The next morning, survivors clean up the carnage. Exhausted, Lily returns to her car where The Swede is waiting for her. He attacks and pins her down. “Cullen will kill you,” she vows. “This is all for him,” The Swede says as he strangles her. He tips a candle over as he leaves.
In present-day, Cullen tells the interrogator that he protected the bridge, not the town, because it was a strategic asset while the town was replaceable. “And its inhabitants?” asks the interrogator. “Replaceable,” says Cullen.
In Lily’s burnt train car, Cullen sits by her body. He carries her corpse through town, leaving it at the church.
The Swede and Cullen walk out on the bridge, where Cullen ties a noose around The Swede’s neck. “I was surprised that you made it so easy to take her from you,” The Swede taunts, “It was inexplicably pleasurable.” Cullen replies, “Not as much as it will be to see you swing.” But before Cullen can secure the rope, The Swede jumps into the river and floats away.
The interrogator tells Cullen that the President has ordered railroad construction to continue, and asks if Cullen would take over Durant’s position and “finish this road.”
Cullen ties a red sash around a rail marker and stakes it next to the bridge, then walks into the distance.