Someone new arrives in Hell on Wheels that turns everything off its tracks. Eva gets caught up between Mr. Toole and Elam.
In the aftermath of tragedy, Lily and Cullen strategies methods for maintaining order in Hell on Wheels. Elam makes plans for the future.
Durant must save the railroad while also fighting for his own life. Cullen fights to save an old friend who has drifted aimlessly.
One of the members of the travelling town is murdered and Cullen is tasked with finding the internal threat.
Cullen attempts to maintain order while Mickey's and Sean's lives are in danger; Lily and Elam clean up a mess they made.
Durant faces a threat to the rolling city, while a terrible crime leads Lily and Elam to join together in order to get justice.
Cullen must deal with his transgressions and Elam isn't happy about his decision. With Lily now a major force in the design of the railroad, she and Durant push the railroad west.