The Rough Riders--Buck Jones, Raymond Hatton and Rex Bell--endeavor to provide a wagon train safe passage through Indian country. With Jones heading the caravan and Bell and Hatton working undercover, the threesome discover that the "savages" planning to attack the settlers are actually renegade whites. The criminals' target is the shipment of railroad supplies being carried in one of the wagons. Normally, the third "Rough Rider" would have been played by Colonel Tim McCoy, but when McCoy was called to active duty in World War II, he was hastily replaced by old-time western star Rex Bell. Dawn on the Great Divide was the last film for Buck Jones, who was killed in the infamous Coconut Grove fire shortly before the film was released.