Diablo's Run is a western revolving around the theme's of right vs. wrong, progress vs. status quo and idealism vs. outright survival.
At the end of the Civil War, two 15 year-old Confederate soldiers surprise Union Captain Jonathon Silverton. Nervous and unsure, the boys aim their fidgety rifles, but in a move of unparalleled quickness, Jonathon draws his pistol and the two confederates fall dead. Disgusted, Jonathon vows to never kill again.
He returns to Julesburg, Colorado, happy to be home and looking forward to living a normal life, but something isn't quite right. Jonathon spots an Indian Chief on a distant ridge, only to see him vanish. His wife, Beth, and daughter are sick, the medicine isn't helping and the townsfolk think he's acting strangely.
Not to mention that Sheriff Hawkins and his deputies are spread thin and outnumbered by henchmen for the railroad baron, the Kelley Gang, who continues to wreak havoc on the town and those not willing to sell their valuable land, such as Jonathon. Upon hearing this, Beth appeals to him to teach their seven year-old son, Scottie, how to shoot, but Jonathon stands firmly against it.
The next day, the Sheriff is forced into a showdown with Kelley and his men, but the Sheriff gets it. Feeling confidant and without authority, the Kelley gang ratchets up their assault on those folks unwilling to sell.
Meanwhile, the town doctor delivers the most devastating news to Jonathon making it clear why everyone was looking at him in such a strange way. Jonathon returns home to find his ranch on fire and no sign of his family. He again spots the Indian Chief in the distance and understands what he has to do.
Jonathon grabs his gun and heads to town.
The showdown is set.