The outlaw Johnny Finger, known as The Rumpo Kid, rides into Stodge City and kills three people in a shootout. The Mayor, Judge Burke, tells him that drinking and firearms have been outlawed. The Kid flouts the edict and is given a room in the local saloon by Belle, the Madame. The judge enlists the help of Sheriff Earp, who has very poor eyesight and is hard of hearing. The Sheriff confronts the Kid and is killed. Soon outlaws controlled by the Kid have overrun the town and the judge writes to Washington requesting a Law Marshall to come and restore order.
The accident-prone Marshall P. Knutt, a British plumber looking for work, is mistakenly sent to Stodge City to take care of the problem. On the stagecoach he meets Annie Oakley, who is heading to the city to avenge the death of her father, Sheriff Earp. When the Kid hears that a Marshall is on his way, he convinces the local Indian tribe to attack the stagecoach. Knutt tries to help, but Annie's shooting skills eventually repel the Indians after she kills three of them, although she lets him take the credit.
Annie takes a room at the hotel, while Marshall is housed at the jailhouse. The Mayor soon realises the misunderstanding but decides to keep Marshall on thanks to his newfound reputation as an Indian killer. The Kid goes to welcome the new Marshall, telling him outlaws are planning to steal cattle that night from Sam Houston's ranch. Marshall is unable to collect a posse and so the Kid gives him two of his men. They find the stolen cattle and then leave Marshall there while they seek help. The Kid sets him up, making it look like he is one of the rustlers. Houston is about to hang him for the offence when Annie, disguised as a cowboy, rescues him.
Some days later Marshall is run down in the street by the Kid's men, and is assumed killed. Annie takes a job as a singer at the saloon. Belle becomes jealous of the Kid's interest in her. Annie discovers that the Kid shot her father and arranges to meet him that night. Big Heap arrives at the saloon in search of whisky and is soon so drunk that he admits that the Kid had him attack the stagecoach. The barman hides him in a backroom. Marshall arrives to arrest the Kid, having matched the horse that ran him down and that of the cattle rustlers with one of the Kid's. He claims to have lent it to Big Heap, but after Marshall leaves, the Kid discovers that Big Heap is now in jail. He sends the barman to let Annie know that he won't be able to see her. When the barman knocks on her door, she kills him by mistake, so she gives herself up to Marshall. She finds Belle trying to seduce him and the two women start fighting. They are soon joined by one of the Kid's girls from the saloon, sent to keep Marshall occupied while they spring Big Heap from jail. While they all fight, the jail is blown up with dynamite. Marshall arrests the Kid and his men, but they trick him and lock him in his own cell.
The Kid and his men kidnap the Mayor and discover Marshall's true identity. The Kid ties the Mayor to his horse, sending him back to town to tell Marshall that he will come for a final showdown at high noon. Annie tries to get Marshall to leave town and admits that she was the one who really shot the Indians and who saved him from the lynch mob. Despite this, he decides to stay and in the few hours remaining gets her to train him in using a gun. The Kid and his men arrive in town, but Marshall picks them off one by one, using the sewers as a hiding place. He arrests the Kid, but he escapes when he is whisked away by Belle on horseback, who then rides out of town. Annie tells Marshall how proud she is of him, before he accidentally shoots himself in the foot.
