Darby Buckingham, the West's hardest hitting, toughest fighting, fastest thinking hero, now charges into what threatens to be his most unbeatable challenge: helping the Union Pacific win the great railroad race across the continent. With time running out, the Derby Man must overcome ferocious Sioux and Cheyenne, brutal weather and terrain, the treacherous Missouri River and the toughest collection of men ever assembled to lay track. And, if that isn't enough, then he must face the most dreaded danger of all - sabotage!