Katherine Fullerton Gerould

Fox's immediate follow-up to its successful early-talkie western In Old Arizona was 1929's Romance of the Rio Grande. The story focuses on the Alvarez family of Mexico, specifically fabulously wealthy Don Fernando. Intending to bequeath his vast fortune and estate to his long-estranged grandson Pancho, Don Fernando must contend with his ne'er-do-well nephew Juan.

When old rancher Cordoba's grandson is murdered, the Cisco Kid takes his place to find who's trying to take over the ranch.

A cowboy estranged from his family and unsure of his heritage becomes a hero and falls for a beautiful Mexican beauty.