El Paso Stampede follows federal Marshall Rocky Lane (Allan Lane) and his horse Black Jack as they travel alongside the Mexican border during the Spanish-American War in search of cattle rustlers. Rocky soon gets a job with a local merchant named Nugget Clark (Eddy Waller). He finds out that the merchant's helper has been feeding cattle shipment information to the local dentist named Mason "Doc" Ramsey (Alden 'Stephen' Chase). The "Doc" soon becomes Rocky's number one suspect. Is the town dentist responsible for all of the missing cattle? Can Rocky find adequate proof to arrest all of the cattle rustlers and their mysterious leader? This film is jam-packed with plenty of action sequences to satisfy all of the die-hard Western fans. The film was directed by Harry Keller and written by Arthur E. Orloff. It stars a talented cast consisting of Allan Lane, Black Jack, Eddy Waller, Phyllis Coates and Stephen Chase.