Breakheart Pass

When diphtheria breaks out at Fort Humboldt, a train is dispatched with medical supplies and relief troops. Also on board are Utah's governor, his mistress, a marshal and his prisoner, outlaw John Deakin . As the train passes through the mountains, soldiers go missing, telegraph lines are cut and it's discovered that there is no epidemic. There's a conspiracy afoot, and it's up to Deakin, actually a federal agent, to expose it.