Five days ago, the blowing up of the express office safe in Burnt Timbers, Montana, had gone off without a hitch for the four members of the Buck Streeter gang, netting them $28,000. Since then they have taken refuge in an abandoned shack on a plateau above the town of Brigham in northern Wyoming. With its bank and express office across the street from each other and lacking any telegraph for communication, Brigham seems like the perfect place to stage their next robbery before laying low for a while.

Streeter is worried about their newest but oldest gang member, Frank Reno, who suffers from consumption and whose coughing throughout the night makes sleep difficult for them all; they need their rest in this tough, cold high country. Still, the gang is confident, and they take their time visiting and studying the lay of the land in Brigham. What they haven't taken into consideration is the snowstorm heading into northern Wyoming and, even more significantly, the determination of US Marshal John Galloway.

Although eighteen years as a lawman has worn down the aging Galloway, he has no fear of death, and he is committed to stopping the gang's spree of robbing and terrorizing small towns across the West, which has taken him from Texas to the Pacific Northwest to Montana. With orders coming from the Denver office, Galloway, who has learned everything he can about the four, has followed his instincts from Burnt Timbers to northern Wyoming. Galloway is convinced that Brigham will be the gang's next target, but as the icy storm sets in, the question becomes when they will strike.