There Was a Young Lady

Elizabeth Foster, a highly efficient secretary, effectively runs the diamond merchant firm. When her boss, David Walsh, buys a diamond ring from a street vendor, he is told the stone is paste and worthless, humiliating him. The incident foreshadows the precarious world surrounding the firm and Walsh's reluctance to propose.

Elizabeth reveals a bold plan to rescue the firm by buying the duke’s family jewels for £70,000, with only £7,000 due upfront. She notes there may be a buyer willing to pay as much as £90,000 later. Walsh refuses to back such a risky scheme, fearing to mortgage his mother's house, and Elizabeth quits.

As Elizabeth leaves the office, she stumbles into a smash-and-grab robbery in progress on the street. She blocks the back door of the gang's getaway car and is forced to climb inside at Joe's insistence.

The gang promises her release if she helps them elude the pursuing police car after the escape. She cooperates, guiding their escape, but Johnny reneges on the promise and takes her to their hideout in the countryside.

Elizabeth is taken to the gang’s hideout, a countryside mansion in Sussex. There she meets Arthur, the fourth member of the gang, and begins to glean how they operate.

She writes a message on a pound note, a clue only noticed when the farm worker tries to spend it in a pub. The worker helps the gang reach the mansion by hay wagon, facilitating their cover as Elizabeth’s plan unfolds.

Elizabeth remains a prisoner for a few days, using her knowledge to predict how their future smash-and-grab will fail and to improve their living conditions. The gang, except Johnny, begins to respect her and listen to her insights.

Elizabeth persuades the gang to follow a plan devised by Arthur, and the group begins to change how it operates. Her leadership steadily shifts the balance of power within the gang.

The gang robs Elizabeth’s former employer and steals the jewellery Walsh had bought from the duke, exposing Walsh's failure to insure the jewels. The heist illustrates the growing boldness and risk of their operation.

Following Elizabeth's message, Walsh launches a rescue operation and retrieves Elizabeth along with the stolen jewels. The rescue confirms Elizabeth’s influence and the viability of their plan.

Several years later, Elizabeth and Walsh are happily married and prosperous, having bought the mansion where Elizabeth was imprisoned. The former gang now serves as trusted servants in their household, completing the couple's remarkable turn of fortune.