After an embezzling banker / murderer sets up Curry and Heyes to take the fall for his crimes, the boys try to clear themselves by playing on his greed with a salted diamond field.

The passengers of a coach are taken hostage at Diablo Station by four cowboys. Not discussing their ultimate goal, they keep Heyes and the Kid and the others tied up, just waiting.

Soon, the goal becomes very clear to Heyes. The leader wants to avenge his brother's death - upon sheriff Lom Trevors. Can Heyes and the Kid, or any of the other passengers warn Lom before he arrives?