In season four of AMC's top-rated drama, Hell freezes over. Following the brutal winter of 1868, the railroad is at a standstill and restless workers wreak havoc on Cheyenne. Cullen Bohannon is trapped in a fort with a pregnant wife and the Swede. Thomas Durant is broke and Elam Ferguson is presumed dead. The task of uniting America by rail remains undone and the costs and consequences are rising, for everyone.