Originally Aired: October 12, 1958

Gunsmoke #340, "Doc's Showdown," begins with tragedy when young Lemmy Woods is brought home to his mother Sarah, shot in the back and tied to his horse like a butchered animal. Doc Adams arrives to treat the mortally wounded boy, learning from Sarah that Lemmy had decided to quit riding with some dangerous companions that very morning. Despite Doc's efforts, Lemmy dies before he can reveal who shot him, leaving Sarah grief-stricken and Doc determined to see justice done. When Matt Dillon cautions Doc to stay out of the investigation, the stubborn physician hatches a dangerous plan of his own.

Doc begins spreading word around Dodge City that Lemmy talked before dying and revealed his killer's identity. Despite warnings from both Matt and Kitty that he's making himself a target, Doc persists in his reckless scheme to flush out the murderer. When a young boy arrives to fetch Doc to the Woods place, claiming Sarah is sick, the trap appears to be set. Doc heads out alone, knowing full well he may be riding into an ambush, while back in town Chester worries about the doctor's uncharacteristic and perilous behavior.