Roy Rogers and Trigger Sunset in the West

Roy puts a stop to gun smuggling. Songs include the title song, "When a Pretty Girl Passes By," and "Rollin' Wheels."

Near the border, outlaws are hijacking trains and using them to transport large quantities of rifles. Roy gets involved when the train that was to pick up his cattle fails to stop. Helping out the Sheriff, Roy brings in a suspect. He identifies him as a wanted man but the outlaw escapes with Roy as a hostage. Roy is taken to the gang leader's house where another hijacking is being planned. They also plan to get rid of Roy.