Adventuress Eleanor Marsh needs a quick infusion of cash to maintain her role as a wealthy American widow and the toast of London society, and marriage with Philip Hardy would supply those funds, so she runs an elaborate con on the eve of Philip's engagement to Lena Grey and manages to supplant Lena in Philip's affections. But the promise of future payment does not satisfy Eleanor's creditors, so she must steal and pawn Philip's family diamonds, setting in play a sequence of sudden changes of fortune for everyone involved.