Fifteen-year-old Will Braddock works as a hunter for his uncle's survey team, as the transcontinental railroad extends across Wyoming in 1868. Paddy O'Hannigan is determined to get even with those who caused the death of his father—which means Will, his uncle, and former slave Homer Garcon. And Paddy has other nefarious designs: he intends to blow up presidential candidate Ulysses S.Grant's train on the general's campaign trip into Wyoming. After saving a German count from a bear attack, in which he himself is badly mauled, Will must immediately turn his attention to his human opponent, the deadly and ruthless Paddy O'Hannigan.

In Golden Spike, the final book in The Iron Horse Chronicles trilogy, Will Braddock is working for the Union Pacific Railroad as it races west to join the Central Pacific. Will's archenemy, Paddy O'Hannigan, is determined to carry out his vendetta to kill Will, Will's uncle, and Homer Garcon, all of whom he blames for his own troubles. Paddy is also desperate for money and sees a chance to get rich when he learns that Leland Stanford, president of the Central Pacific Railroad, is bringing a golden spike to the ceremony to mark the completion of the first transcontinental railroad. Paddy's plan to steal the spike will have grave consequences for Will and his friends...if they can't stop him in time.