Set in the post-American Civil War era, "Hell on Wheels" follows Cullen Bohannon, a former Confederate soldier and former slave owner on a quest to find and kill the Union soldiers who murdered his wife and young son. His vengeful journey leads him to the Union Pacific Railroad's westward-moving construction camp, known as "Hell on Wheels." Along the way, Bohannon encounters ruthless bosses, former slaves seeking their place in a changing America, greedy railroad executives, and indigenous populations fighting to protect their land. As the series progresses, Bohannon shifts from a man driven purely by vengeance to someone deeply entangled in the massive, corruption-riddled engineering feat of the Transcontinental Railroad. He rises through the ranks to become the chief engineer, grappling with moral compromises, complex political pressures, and evolving relationships with colorful and dangerous figures like the cunning Thomas "Doc" Durant and the fiercely independent Elam Ferguson.