The film opens with the narrator (Dale Robertson in an early, uncredited role) laying the foundation of the story.
In 1871, six convicts escape from a Carson City prison. One of them freezes to death during a blizzard. The others—Canfield, Greer, Cockerell, Anderson and Maxwell—make it to Lake Monte Diablo, where eight women live in a settlement while their men are away prospecting. Granny is the elder, watching over Marcia, Rachel, Barbara, Susan, Harriet, Mary, and Millie.
Frightened, the women reluctantly permit them to use an empty cabin. Granny hides all the guns except one when they realize that the men are escaped convicts. Canfield has returned here for a reason; the other convicts think that he has money hidden somewhere nearby. Canfield was convicted of killing a mine owner, and $40,000 is missing.
Canfield learns that Marcia, to whom he is attracted, is engaged to be married to a man named Rudy Schaeffer. Canfield claims Rudy took the $40,000 and committed perjury to get Canfield convicted and sentenced to hang. Canfield reveals that he has returned to kill Schaeffer.
A barn catches fire due to Rachel's nervousness. After the convicts rescue the animals, the women treat them more kindly. Canfield is trustworthy, but the other four continue plotting.
Later, Canfield manages to take Granny's gun. Marcia rides off, so Canfield follows and catches up to her. They eventually embrace and kiss. He tells her that Morgan, a mine owner, had swindled him out of the money. When he came to talk to Morgan about it, Morgan pulled a gun on him, they scuffled and the gun went off, killing Morgan. Schaeffer witnessed this, but claimed that Canfield had killed Morgan in cold blood, so Schaeffer could keep the money himself. Rachel refuses to believe it.
While Canfield and Marcia are away, Johnny Greer charms Rachel, Schaeffer's unmarried sister, into revealing where Granny hid the other guns. He, Cockerell and Anderson arm themselves and wait for Canfield.
On the way home, the men of the town stop in a saloon. Rudy Schaeffer spots a wanted poster, so the alarmed men race back to their families.
Clyde Maxwell, the youngest convict, a psychotic, cannot control his murderous impulses whenever someone resists him. He takes Barbara on a long walk and tries to kiss her. Barbara tries to pull away and he pulls out a machete. Canfield, riding back with Marcia, hears Barbara's cries and arrives in time to intervene. In the ensuing struggle, Maxwell stabs Canfield in the shoulder. Maxwell chases after Barbara, but the other women, who are out looking for her, kill him with a pitchfork. Greer has no trouble taking the wounded Canfield's gun, and his men take Canfield.
Rachel finds the $40,000 in a trunk belonging to her brother, Rudy. She gives the money to Marcia to give it to Greer to stop beating Canfield and leave. However, just when Greer, Cockerell, and Anderson go to leave, Schaeffer and the other men arrive back in the small town and confront the convicts.
In the ensuing gunfight, Cockerell and Anderson are shot. Greer flees up the mountain, chased by all but Schaeffer and Canfield, but he drops the $40,000 while climbing. He tries to pick it up, is shot, and falls to his death. Schaeffer, knowing that his secret has been uncovered, tries to sneak away. Canfield comes up behind him and, at gunpoint, orders Schaeffer to confess publicly when the rest of the men come back. Marcia runs up behind, screaming for Canfield. As he half turns to her, Schaeffer spins around and draws his gun, forcing Canfield to shoot him. Canfield then gives his gun to Marcia.
The sheriff and his posse arrive, as Marcia forces the group to decide about Canfield. When the sheriff asks about the five fugitives (they found the frozen sixth man earlier), Granny shows him five newly-dug graves (the 4 convicts and Schaeffer). The others, including a somber Rachel (despite the death of her brother), all agree that they have no other comments, and the sheriff is satisfied.
The narrator claims the story is true and reveals the lake was renamed Convict Lake.
