In the 1870s, while flirting with saloon singer Lin Conner and her friend, Julie Ann McCabe, in Barnaby's general store, Johnny Drum, a fugitive wanted for murder, is confronted by Sheriff Sam Borden. When Sam attempts an arrest, Johnny shoots him, then flees the store. Johnny then steals Julie's horse and eludes Deputy Tap Lawrence's posse. On the trail, Johnny is attacked by Sioux warriors, but is saved by Whit Lacey, an outlaw accused of raiding Eben Martin's mining operation. Aware that Johnny, too, is a wanted man, Whit convinces him to participate in a fake marriage to his sweetheart, Julie, whom Tap has been doggedly following in the hope that she will lead him to Whit. Posing as Julie's old flame, Johnny Corrigan, Johnny returns to town, where he and Julie are married by a phony justice. Soon after, Johnny meets secretly with Sam, whom he pretended to shoot as part of an Army undercover operation, and speculates that an inside source has been giving Whit information about Martin's mines. Johnny then leaves town with Lin and Julie, who happily reunites with Whit on the trail. To Julie's dismay, Whit announces that he has one more job to do before they can head for California and makes plans with Calico, his right-hand man, to steal horses from a passing herd. When Whit tries to sell the stolen horses to an Army officer, a cowboy wounded during the ambush identifies him as a horse thief, and Whit barely escapes with his life. That evening at Whit's hideout, Whit informs Julie that she, Johnny and Lin have to return to town for a few days. In town, Johnny, whose eyes were covered coming and going from the hideout, gives Sam some drawings he made of the surrounding area, hoping that a surveyor will be able to pinpoint the hideout's exact location. Later, the wealthy Martin proposes to Lin, but to Johnny's relief, she turns him down. Johnny then makes his own proposal and kisses the surprised singer. The next day, after Johnny buys a supply of ammunition and he, Lin and Julie leave for the hideout, Tap tells Martin that Sam's murder was faked. Unknown to Tap and Sam, Martin is behind the raids on his mine, which he hopes to sell for a large profit. After Martin sends a messenger to Whit's hideout with news of Johnny's impersonation, Whit, who has grown as fond of Johnny as Johnny has of Whit, allows him to escape. As Whit, Calico, Julie and Lin flee the hideout, they are captured by Sam and his deputies. Sam takes Julie, Lin and his two prisoners, who have refused to reveal who sent the note about Johnny, to an Army outpost, where they are to be jailed temporarily. Out of loyalty to Julie, Lin begs Johnny to release Whit, and when Johnny refuses, she rejects his proposal. Having recently arrived at the outpost, Martin, fearing exposure, incites the locals to form a lynch mob against Whit and Calico. Just as they are about to hang the prisoners, a band of Sioux Indians, led by Red Cloud, shoots a flaming arrow of war into the outpost. Johnny frees Whit and Calico to help in the fight, and as the three men prepare to reclaim an outer building from the Sioux, Calico forces Martin to accompany them. After the men overwhelm the Indians guarding the building, Calico exposes Martin as his boss. Julie then makes a dash for the building and is reunited with Whit, who is compelled to knock her out in order to return her to the outpost. Johnny orders Martin to carry the unconscious Julie back, and when Martin refuses, Whit shoots him. Johnny then volunteers, but as he runs toward the outpost, an arrow pierces Julie's back, killing her. The well-armed Indians then blast a hole in the outpost and swarm inside, and Whit and Calico are killed during the fiery battle. After much bloodshed, Cavalry troops arrive and subdue the Indians. Later, Johnny is discharged from the Army, and he and Lin look forward to married life on Johnny's Texas ranch.