A cowboy is arrested for rustling cattle. A lynch mob is formed by his buddy to try and arrange an escape in the confusion. Things go wrong.

Cowboy Larry O'Day and his sidekick Lucky Smith happen upon a distraught Barbara Hartwell, who is about to be arrested for the murder of her uncle. With Barbara behind bars, Larry is determined to find the real killer and soon finds himself in the middle of a mystery involving crazed German entomologists and a smuggling ring bringing Chinese "picture girls" across the Mexican border for sale to wealthy Chinese bachelors.