Saloon owner Kent (Brian Donlevy), the unscrupulous boss of the fictional Western town of Bottleneck, has the town's sheriff, Mr. Keogh (Joe King), killed when Keogh asks one too many questions about a rigged poker game.
Kent and "Frenchy" (Marlene Dietrich), his girlfriend and the dance hall queen, now have a stranglehold over the local cattle ranchers.
The crooked town's mayor, Hiram J. Slade (Samuel S. Hinds), who is in collusion with Kent, appoints the town drunk, Washington Dimsdale (Charles Winninger), as the new sheriff, assuming that he will be easy to control and manipulate.
However, Dimsdale, a deputy under the famous lawman Tom Destry, promptly swears off drinking, and is able to call upon the latter's equally formidable son, Tom Destry, Jr. (James Stewart), to help him make Bottleneck a lawful, respectable town.

Destry arrives in Bottleneck with Jack Tyndall, a cattleman, and his sister, Janice.
Destry initially confounds the townsfolk by refusing to strap on a gun and maintaining civility in dealing with everyone, including Kent and Frenchy.
This quickly makes him a disappointment to Dimsdale and a laughingstock to the townspeople; he is mockingly asked to "clean up" Bottleneck by being given a mop and bucket.
However, after a number of rowdy horsemen ride into town shooting their pistols in the air, he demonstrates uncanny expertise in marksmanship and threatens to jail them if they do it again, earning the respect of Bottleneck's citizens.

Through the townsmen's evasive answers regarding the whereabouts of Keogh, Destry gradually begins to suspect that Keogh was murdered.
He confirms this by provoking Frenchy into admitting it, but without a location for the body, he lacks any proof.
Destry therefore deputizes Boris, a Russian immigrant who Frenchy had earlier humiliated, and implies to Kent that he had found the body outside of town "in remarkably good condition".
When Kent sends a member of his gang to check on Keogh's burial site, Boris and Dimsdale follow, capture, and jail him.

Although the gang member is charged with Keogh's murder (in the hope that he would implicate Kent in exchange for clemency), Mayor Slade appoints himself judge of the trial, making an innocent verdict a foregone conclusion.
To prevent this, Destry calls in a judge from a larger city in secret, but the plan is ruined after Boris accidentally gives away the other judge's name in the saloon.
Kent orders Frenchy to invite the deputy to her house while other gang members storm the sheriff's office and cause a breakout; now in love with Destry, she accepts.
When shots are fired, he rushes back, to find the cell empty and Dimsdale mortally wounded.
Destry returns to his room and puts on his gun belt, abandoning his previous commitment to nonviolence.

Under Destry's command, the honest townsmen form a posse and prepare to attack the saloon, where Kent's gang is fortified, while Destry enters through the roof and looks for Kent.
At Frenchy's urging, the townswomen march in between the groups, preventing further violence, before breaking into the saloon and subduing the gang.
Kent narrowly escapes, and attempts to shoot Destry from the second floor; Frenchy takes the bullet for him, killing her, and Destry kills Kent.

Some time later, Destry is shown to be the sheriff of a now lawful Bottleneck, repeating to children the stories that Dimsdale told him of the town's violent history.
He jokingly tells a story about marriage to Janice, implying a marriage between them will soon follow.
 As the movie ends a child sings "Little Joe" the song Frenchy was singing at the beginning of movie indicating Destry will never forget Frenchy.
Saloon owner Kent (Brian Donlevy), the unscrupulous boss of the fictional Western town of Bottleneck, has the town's sheriff, Mr. Keogh (Joe King), killed when Keogh asks one too many questions about a rigged poker game. Kent and "Frenchy" (Marlene Dietrich), his girlfriend and the dance hall queen, now have a stranglehold over the local cattle ranchers. The crooked town's mayor, Hiram J. Slade (Samuel S. Hinds), who is in collusion with Kent, appoints the town drunk, Washington Dimsdale (Charles Winninger), as the new sheriff, assuming that he will be easy to control and manipulate. However, Dimsdale, a deputy under the famous lawman Tom Destry, promptly swears off drinking, and is able to call upon the latter's equally formidable son, Tom Destry, Jr. (James Stewart), to help him make Bottleneck a lawful, respectable town.
Destry arrives in Bottleneck with Jack Tyndall, a cattleman, and his sister, Janice. Destry initially confounds the townsfolk by refusing to strap on a gun and maintaining civility in dealing with everyone, including Kent and Frenchy. This quickly makes him a disappointment to Dimsdale and a laughingstock to the townspeople; he is mockingly asked to "clean up" Bottleneck by being given a mop and bucket. However, after a number of rowdy horsemen ride into town shooting their pistols in the air, he demonstrates uncanny expertise in marksmanship and threatens to jail them if they do it again, earning the respect of Bottleneck's citizens.
Through the townsmen's evasive answers regarding the whereabouts of Keogh, Destry gradually begins to suspect that Keogh was murdered. He confirms this by provoking Frenchy into admitting it, but without a location for the body, he lacks any proof. Destry therefore deputizes Boris, a Russian immigrant who Frenchy had earlier humiliated, and implies to Kent that he had found the body outside of town "in remarkably good condition". When Kent sends a member of his gang to check on Keogh's burial site, Boris and Dimsdale follow, capture, and jail him.
Although the gang member is charged with Keogh's murder (in the hope that he would implicate Kent in exchange for clemency), Mayor Slade appoints himself judge of the trial, making an innocent verdict a foregone conclusion. To prevent this, Destry calls in a judge from a larger city in secret, but the plan is ruined after Boris accidentally gives away the other judge's name in the saloon. Kent orders Frenchy to invite the deputy to her house while other gang members storm the sheriff's office and cause a breakout; now in love with Destry, she accepts. When shots are fired, he rushes back, to find the cell empty and Dimsdale mortally wounded. Destry returns to his room and puts on his gun belt, abandoning his previous commitment to nonviolence.
Under Destry's command, the honest townsmen form a posse and prepare to attack the saloon, where Kent's gang is fortified, while Destry enters through the roof and looks for Kent. At Frenchy's urging, the townswomen march in between the groups, preventing further violence, before breaking into the saloon and subduing the gang. Kent narrowly escapes, and attempts to shoot Destry from the second floor; Frenchy takes the bullet for him, killing her, and Destry kills Kent.
Some time later, Destry is shown to be the sheriff of a now lawful Bottleneck, repeating to children the stories that Dimsdale told him of the town's violent history. He jokingly tells a story about marriage to Janice, implying a marriage between them will soon follow.  As the movie ends a child sings "Little Joe" the song Frenchy was singing at the beginning of movie indicating Destry will never forget Frenchy.
Destry Rides Again