 Farrell (Philo McCullough) is taking advantage of the proximity of the rancho of Don Jose (Bruce Covington) to the Mexican border by smuggling Chinese across the line into the United States. Dave (John Litel), a border patrol officer posing as a tramp, is out to put an end to Farrell s activities. He is aided by police dog Rinty (Rin-Tin-Tin) who gets to growl and show his teeth a lot. Pepita (Armida), the Don s daughter, gets to strum her guitar and sing a couple of songs.