An agent of an unspecified foreign power John Miljan plots to take over California during the confusion of the American Civil War. He enlists Morrell Henry Wills and his Overland Raiders to block any news from reaching the East, a scheme that involves rustling stagecoaches and Pony Express horses from relay stations to sever every line of communication. In response, Bill Hickok Roy Rogers is sent to one relay station in hopes of keeping the ponies out of Raider hands and preventing a wider disruption of the war effort.
Just as Bill finishes off the last of the Raiders who attacked his post, Calamity Sally Payne and Gabby George 'Gabby' Hayes, seasoned horse traders for the relay stations, ride in with their Indian helpers. The two allies provide aid and medical attention, and Bill’s injuries force them to stay nearby for a time. Into this tense moment arrives Bill’s old fiancée, Louise Mason Julie Bishop, bringing memories of a broken engagement rooted in wartime loyalties. Louise comes with a desire to make amends, and she and Bill briefly suspend the fighting between North and South as they entertain thoughts of a future together and begin to plan a wedding.
Meanwhile, Marshal Evans heads the relay network and has a broader task: escort a shipment of gold to the East to sustain the Federal war effort. Bill realizes that carrying the gold himself would invite an entirely new wave of danger, so he delegates the job, sending Gabby and Calamity with the gold while he pretends to take it himself to mislead the raiders. The ruse backfires when Louise informs Tower [John Miljan] that Bill is not personally bearing the gold, a disclosure that increases the Raiders’ confidence and places Gabby in the line of fire. The Raiders strike Gabby and steal the gold, leaving Bill scrambling for answers and wondering what went wrong.
Bill returns to town to learn Gabby’s fate and to gauge the damage. The Marshal demands an explanation, and Bill asks for half an hour to uncover the truth. In the aftermath, Tower exploits the confusion, convincing the men that Bill is secretly at the head of the Raiders and that he’s attempting a getaway with the stolen gold. Gabby, who overhears their plotting, rides to warn Bill and help him reclaim the truth. Although Bill manages to slip away for a time, he is ultimately captured when he returns to Tower’s office to search for the missing evidence.
Gabby helps him escape, and the two glimpses Tower fleeing with the gold and the Raiders in pursuit. They rally the posse and press on, determined to correct the misperception and recover the loot. As the Civil War comes to a close, Tower and the Raiders are finally brought to justice, and balance is restored. In the end, the long and perilous struggle gives way to a quiet happiness: Bill Hickok and Louise Mason celebrate a wedding that marks a new beginning for both of them and for the nation they fought to heal.
