The Twilight Zone Mr. Denton on Doomsday Starring Dan Duryea

Mr. Denton on Doomsday" is episode three of the American television anthology series The Twilight Zone. It originally aired on October 16, 1959 on CBS. It was the first Twilight Zone episode to be rerun.
Al Denton was once known as the quickest draw in town, but riddled with increasing guilt over the losers in his gun duels (one of whom was a teenage boy), he became an alcoholic wreck and the laughingstock of the community. A mysterious salesman named Henry J. Fate causes Denton to inexplicably regain his expert shooting touch and once again inspire the respect and awe of the townsfolk; Denton explains to Liz, a saloon girl, that this will only cause reputation-hungry gunslingers from miles around to seek him out and, inevitably, kill him. He cleans himself up and goes sober but only, he says, so as to die with dignity. Just as Denton predicted, soon enough a challenge is delivered which Denton dares not refuse.

The still-weary and not-so-sure-handed Denton practices in the desert for his suicidal duel, but he misses his targets miserably and concludes that he must skip town. As he packs his things and tries to flee under the cover of night, he strikes up a conversation with Fate, who seems to know things about Denton and offers him a way out. Fate offers him a potion guaranteed to make the drinker the fastest gun in the West for exactly ten seconds. Denton is skeptical but Fate goads him into drinking a free sample, after which Denton immediately realizes its benefits.

At the appointed time, Denton faces his challenger, Pete Grant, a brash young gunfighter. Denton downs his potion only to find his opponent holding an identical empty bottle. Grant and Denton both realize that Fate tricked them, but it is too late to back out of the duel. Each man shoots the other in the hand, causing injuries which are minor but forever ruin both men's ability to pull a trigger.

Denton tells his young opponent that they have both been blessed because they will never again be able to fire a gun in anger. He tells Liz that Grant is lucky because he was given this lesson early. Henry J. Fate tips his hat to Denton and rides quietly out of town.