John Deakin is a secret agent posing as a thief on his way to jail. Boarding a special government train in handcuffs, he begins a terrifying journey that brings him face-to-face with death. Various passengers on an 1873 train across the frozen west to Fort Humboldt turn out to have smuggling and murder in mind.

Lt. Col. Kirby Yorke is the commander of a cavalry outpost on the Rio Grande. When Yorke's estranged wife arrives to pull their teenage son out of the army, they decide to give their marriage another try. Meanwhile, a risky plan to outwit a tribe of warring Apaches puts Yorke in danger of being court-martialed.