In a lawless Western town dominated by the corrupt Kent family, Sheriff Keogh is murdered and replaced by the cowardly Mayor Slade. To project order and legitimacy, Slade appoints the mild-mannered yet resolute Tom Destry Jr. as the new deputy sheriff. Destry, known for his aversion to violence and use of wit and strategy, arrives in town and quickly reveals that he won't be intimidated by the town's outlaws. Early on, he meets saloon entertainer Frenchy, who is initially skeptical of his capabilities. Frenchy, intricately involved with the town's criminal element and Kent’s underhanded schemes, becomes an unlikely ally as Destry begins to stand up against the rampant corruption.

Destry methodically confronts the town's injustices, earning the respect of its citizens while inflating tensions with Kent and his gang. Throughout his cautious approach, Destry unearths evidence related to Sheriff Keogh's disappearance implicating key figures in the town. Frenchy and Destry grow closer as they face numerous dangers, challenging their initial perceptions of loyalty and justice. As Destry’s influence grows, the tipping point approaches where he must choose whether to maintain his non-violent stance or resort to more traditional methods of frontier justice to cleanse the town of its lawlessness once and for all.