The Big Diamond Robbery(1929)

Tom Mix starred in this late-silent Wild West melodrama from poverty row company FBO as a ranch foreman assigned to escort his employer's daughter (Kathryn McGuire) from the big city back to the ranch. The girl, Ellen, is carrying the valuable Regent diamond, and the pair become the target of a gang of thieves led, it turns out, by Ellen's former fiancée Rodney (Ernest Hilliard).