Larry "Buster" Crabbe's "Billy the Kid" is once again unfairly accused of a crime and on the run with friends Fuzzy Q. Jones (Al St. John and Jeff (Dave O'Brien in this low-budget oater from PRC. The three fugitives come across a young boy, Dickie Howard (played by the director's son Joel Newfield), whose father (Richard Fraser) has been wounded. Just then, the sheriff (Ted Adams) arrives to arrest Billy and his friends, whom he suspects of the crime. In Stone City, Dr. Elmo Hagen (Milt Kibbee) mercilessly kills Howard and then reprimands the sheriff for not having finished the job himself. Escaping the rather inhospitable town, Billy and company hide out at the Howard ranch. As Billy learns from Mrs. Howard, the murder of her husband was committed on behalf of the Ranchers Cooperative Association run by Morgan (John Merton), a crook attempting to cheat the local farmers out of their crops. But as Billy also discovers, Morgan is controlled by Dr. Hagen, the real mastermind behind the crimes -- a fact that doesn't bode well for his innocent patients, one of whom, Jeff, nearly dies under the crooked medico's care. In the end, Hagen and his accomplices are unmasked and peace restored to Stone City. Billy the Kid's Smoking Gun was directed by PRC regular Sam Newfield under his usual pseudonym of Sherman Scott.