The film opens with a calm, guiding narrator laying the groundwork for a frontier drama that blends menace and moral consequence. In 1871, six convicts break free from a Carson City prison, with one of them freezing to death in a raging blizzard as the others push toward a remote settlement by Lake Monte Diablo, where eight women remain with their men away prospecting. Edward 'Limey' Cockerell [Cyril Cusack] is among the escapees, along with Jim Canfield [Glenn Ford], Johnny Greer [Zachary Scott], Rudy Schaeffer [Harry Carter], and the others, who converge on a quiet outpost watched over by Granny [Ethel Barrymore]. The women, led by Granny and their elder care, fearfully grant the men the use of an empty cabin while quietly recognizing the danger that accompanies their return.
The group’s arrival unsettles the settlement, and Granny quickly hides most of the guns, keeping only a single firearm as a safeguard. The convicts’ presence disrupts the fragile peace, yet Canfield proves to be the most level-headed of the lot, even as the others plot to uncover a hidden fortune. Canfield has a personal stake in the town’s recent rumors: a missing $40,000 tied to a mine owner named Morgan. He claims that Morgan swindled him and then killed him in a fight that ended with the gunfire that landed Canfield in trouble. Marcia Stoddard [Gene Tierney], a woman of courage and conscience, is engaged to Rudy Schaeffer [Harry Carter], and she struggles to reconcile Canfield’s tale with the rumors swirling around her fiancé’s wealth and moral character. Marcia’s loyalty to truth becomes a central thread in the narrative, even as attraction flickers between her and Canfield.
Amid the tension, a complicated web begins to form. A quiet, unsettling charm emanates from Johnny Greer [Zachary Scott], who works to learn more about the hidden weapons by charming Schaeffer’s sister Rachel [Ann Dvorak], the unmarried sister who lives in the town. Rachel’s willingness to reveal Granny’s hideout triggers a dangerous arms race within the settlement. The men drift between caution and bravado, and a barn fire—stoked by Rachel’s nerves—tests everyone’s resolve while the women work to protect the community and prevent a total collapse of trust.
Maxwell [Richard Hylton], the youngest of the convicts, reveals a more volatile and psychotic streak whenever anyone resists him. He takes Barbara Purcell [Barbara Bates] on a long walk and tries to force a kiss, escalating fear into violent confrontation. Barbara’s struggle to resist is met with brutal danger as Maxwell pulls a machete, and Canfield—riding back with Marcia—hears her cries and arrives just in time to intervene. In the ensuing struggle, Maxwell wounds Canfield with a stab in the shoulder, and he chases Barbara into the night, where the other women—who have gone out to search for her—step in and kill Maxwell with a pitchfork. Greer, now emboldened, is quick to seize Canfield’s weapon, and his gang takes Canfield into their custody.
As the plot thickens, Rachel finds the missing $40,000 in a trunk owned by her brother Rudy and hands it to Marcia to deliver to Greer in an effort to stop the brutal beating Canfield faces and to prevent further bloodshed. Yet the quiet is shattered when Schaeffer and the rest of the men return to confront the remaining fugitives. In a deadly gunfight, Cockerell and Anderson are shot, and Greer flees up the mountain, fiercely pursued by the others. He drops the money en route and is killed when he tries to recover it. With his secret about the money exposed, Schaeffer tries to slip away, only to be confronted by Canfield, who orders him to confess publicly when the group returns. Marcia races toward them, calling for Canfield, but Schaeffer wheels around and forces Canfield to shoot him. Canfield then hands his gun to Marcia.
The sheriff and his posse arrive just as the truth stands before them. The women stand with Granny, who reveals five newly-dug graves—the four convicts and Schaeffer—leaving the others to contemplate the heavy price of deception and greed. The group accepts the outcome with a somber grace, and the sheriff’s examination concludes with a quiet, unspoken consensus. The tale ends with the narrator returning to the stage of the event, declaring that the story is true and revealing that Lake Monte Diablo has been renamed Convict Lake, a stark reminder of the consequences that those lives faced in the wake of that fateful summer.
