An impetuous decision to marry has left the young Lady Caroline widowed and with two estates in her name. She is now in a position to live her life to the full, socialising with London's finest aristocracy, but her unhappy experience has put her off marrying again. Her younger sister, Annabelle, on the other hand, is falling in love with a man who is notoriously unfaithful. But Annabelle refuses to believe it, so Caroline knows she must intervene before she sees her sister fall victim to the same miserable fate she experienced. And so she hires the charming Captain Burnside, a retired British Army officer, to distract her. An adventurer who is both charming and witty, he seems the perfect man to tear Annabelle away from her infatuation. But things don't go quite according to Caroline's plan.