This 1975 Western adventure is a rollicking thriller that has a little bit of everything: mystery, murder, and a treacherous train ride set against the sweeping backdrop of a stunning, snowy frontier…and of course, Charles Bronson.

U.S. Marshall Nathan Pierce is escorting John Deakin, a cheating cardsharp accused of murder, to jail on a train bound for Fort Humboldt in far-away Utah. The train is filled with soldiers traveling to the army outpost to deliver medicine for a diphtheria outbreak and to replenish the fort’s ranks since so many soldiers have already died.

Onboard the train are Governor Fairchild, who runs the Nevada territory; his fiancé Marica Scoville, the daughter of Fort Humboldt’s commander; a railroad representative named O’Brien; a traveling reverend named Peabody; and an army major named Claremont.  

Something is not quite right on this train supposedly on a Good Samaritan mission to deliver medical supplies and personnel. John Deakin has a hunch that there’s a conspiracy brewing, and he should know. He isn’t actually a notorious outlaw—he’s an undercover federal agent.

Things begin to deteriorate quickly as the train moves into the mountains and deeper into the desolate frontier. It seems death rides the rails to Breakheart Pass as several passengers—including many of the relief soldiers bound for Fort Humboldt—go missing or are killed outright.

Deakin soon discovers that the “epidemic” at the army outpost doesn’t even exist. There is no epidemic—and the train isn’t carrying any medicine or medical supplies!

Instead, the treasured cargo onboard is a stolen cache of weapons, including guns, ammunition, and dynamite. This mission is just a set-up for a group of gunrunning outlaws and a tribe of conspiring Indians bent on thievery, exploitation, and murder.

Any innocents who discover the truth are quickly cut down and silenced forever. But what’s even more alarming is that almost everyone on the train is in on the conspiracy!

Now, Deakin must quickly decide who to trust and who to suspect as they rush towards a down and dirty fight to the death. Now the bullets are about to fly at Breakheart Pass!