In rural England during the late 17th century, a social match is set in motion when Barbara Worth is invited by her cousin Caroline to attend the wedding of the wealthy landowner and local magistrate, Sir Ralph Skelton. Barbara’s beauty and wit quickly enthrall Sir Ralph, and before long she ascends to the role of Lady Skelton, much to Caroline’s quiet dismay. At the wedding reception, Barbara encounters a dashing stranger, Kit Locksby [Michael Rennie], and the spark between them becomes instant and undeniable, even though it arrives with the sting of foregone proprieties and consequences.
Life in the countryside afterward proves dull for Lady Skelton, until a visit from her sister-in-law, the formidable Lady Henrietta Kingsclere, stirs old tensions. In a game of Ombre, Henrietta wins Barbara’s prized jewels, including her late mother’s ruby brooch, sparking a sense of wounded pride and daring in Barbara. A casual remark about a notorious highwayman, Jerry Jackson, plants the seed for a dangerous plan: Barbara will masquerade as the famed robber. When she steps into Jackson’s shadow, her disguise is flawless enough to stop Henrietta’s coach and reclaim the lost jewels, and the exhilaration of this deception grips her. She continues to stage these ambushes night after night, growing bolder, until she and the real Jerry Jackson finally meet.
The two conspirators discover a dangerous chemistry; Jackson is amused to find that his masquerading partner is a striking woman, and they soon become lovers and partners in crime. Barbara makes a grim pact not to betray him to her husband, building a dangerous double life where crime and romance intertwine. Their joint ventures yield profit from ill-fated travelers, but a plan to rob a colossal gold shipment goes catastrophically wrong when Barbara shoots and kills one of Sir Ralph Skelton’s tenants. A servant in Skelton’s household uncovers her involvement, yet Barbara deftly convinces him that Jackson forced her into complicity.
Barbara further manipulates the loyal servant’s religiosity, insisting that she longs for an honest, clean life and that he must help her reform. Pretending to be newly devout, she secretly poisons him and, when his illness grows grave and he suspects her deceit, she smothers him with a pillow. Ecstatic at her momentary freedom, she hurries to the inn where she and Jackson once hid, only to find him in bed with another woman. Enraged, Barbara anonymously betrays Jackson’s whereabouts to her husband, and the hunter becomes the hunted: Jackson is captured and sentenced to hang.
In London, Barbara attends the execution with Caroline, who cannot bring herself to watch. On the scaffold, Jackson’s speech laments faithless women without naming Barbara directly. A priest’s note helps Barbara arrange a monetary gift for Jackson’s other woman, but that woman’s carriage is soon attacked, and a riot erupts. Hope flickers when Kit Locksby and Caroline are rescued by the couple’s friends, and Kit is revealed to be engaged to Caroline. Though the gallows end Jackson’s days, his accomplices revive him and the drama intensifies when he breaks into Barbara’s room and rapes her. She pleads with Kit to run away with her, but he will not betray Caroline.
As night falls and Ralph’s coach returns from bringing Caroline and Kit to London, Barbara, now in highwayman gear, waits with a pistol to carry out a final strike. Jackson arrives, intent on warning Skelton, but Barbara turns the threat on him and shoots him dead. He dies with the quip that they will meet again in hell. When the coach finally approaches, Barbara hijacks it, aiming at Ralph, unaware that Caroline and Kit have returned with him and that a fragile truce exists between the two couples. Kit emerges from the coach and fires first, wounding Barbara, who escapes on horseback as Caroline stops Kit from firing again.
Back at the estate, Barbara, mortally wounded, confesses every murder and deceit to Kit and begs him to stay, but he is revolted by what he has learned and departs. In the end, Barbara dies and Caroline and Skelton renew their bond, resolved to put the turbulent past behind them and to look toward a steadier future together.
